CN107923214B - Vacuum Insulating Glass (VIG) unit having pump outlet sealed via metal solder seal and/or method of making same - Google Patents

Abstract

Example embodiments relate to a vacuum insulated glass unit having a pump-out hole seal formed in connection with a solder alloy when reactively reflowed, wetted with a pre-coated metal coating, and/or related methods. These alloys may be based on materials that form a seal at temperatures that do not de-temper the glass and/or decompose the laminate, and/or maintain an airtight seal and a non-porous structure within its volume. SAC, InAg, and/or other preformed materials may be used in various example embodiments.

Description

Vacuum Insulating Glass (VIG) unit having pump outlet sealed via metal solder seal and/or method of making same

CROSS-REFERENCE TO RELATED APPLICATIONS

This application requests us application nos.62/187,797 filed on 7/1/2015 and 15/170,265 filed on 6/1/2016, the entire contents of which are incorporated herein by reference.

This application also incorporates by reference the entire contents of each of U.S. application No.14/145,462 filed on 31.12.2013 and U.S. application No.14/789,444 filed on 1.7.2015.

Technical Field

Exemplary embodiments of the present invention relate to a vacuum insulating glass (VIG or vacuum IG) unit and/or a method of making the same. More particularly, exemplary embodiments of the present invention relate to a VIG unit having a pump-out hole seal formed in conjunction with a solder pre-alloy of the metal while reactively reflowing, wetting, and bonding to a pre-coated metal coating, and/or related methods.

Background

Hermetically sealing the glass substrates to create a vacuum or inert gas environment therebetween is typically accomplished using a barrier so that gas does not enter the glass or metal (e.g., eutectic) material for extended periods of time, typically many orders of magnitude longer than the operating life of the device. It will be appreciated that permeability generally involves two steps. These steps include dissolution and diffusion. For example, hermetic sealing facilitates the removal of water, other liquids, oxygen and other gaseous contaminant molecules from the package, such as, but not limited to, maintaining a vacuum (e.g., VIG window unit, thermal bottle, MEMS, etc.) or sensitive materials, including, for example, organic emissive layers (e.g., for OLED devices), semiconductor chips, sensors, optical elements, etc., which are maintained in an inert atmosphere. The hermetic packaging of the complex interior of these components constitutes an obstacle during post-processing stages of the packaging, such as before pumping and desoldering in VIG window units, final processing steps in the OLED device fabrication process, etc.

Some exemplary VIG configurations are disclosed, for example, in U.S. patent nos.5,657,607,5,664,395,5,657,607,5,902,652,6,506,472, and 6,383,580, the disclosures of which are incorporated herein by reference in their entirety.

Disclosure of Invention

Fig. 1 and 2 show a VIG window unit 1 present and elements used to form the VIG unit 1. For example, the VIG unit 1 may comprise two separate substantially parallel glass substrates 2, 3 with an evacuated low pressure space/chamber 6 attached. The glass sheets or substrates 2, 3 are interconnected by an outer edge seal 4, which may be made of molten solder glass or the like. A set of pillars/spacers 5 may be included between the glass substrates 2, 3 to maintain the spacing of the glass substrates 2, 3 of the VIG unit 1 in view of the low pressure space/gap 6 that exists between the substrates 2, 3.

The pump-out tube 8 may be hermetically sealed to the aperture/hole 10 by solder glass 9 or the like, from the inner surface of the glass substrate 2 to the bottom of an optional groove 11 in the outer surface of the glass substrate 2, or alternatively to the outer surface of the glass substrate 2. A vacuum is connected to the pump-out tube 8 to evacuate the internal cavity 6 to a low pressure below atmospheric pressure. After the chamber 6 is evacuated, a portion (e.g., the tip) of the tube 8 is melted to seal the vacuum in the low pressure chamber/space 6. An optional groove 11 may be used to secure the sealed pump-out tube 8. Optionally, the chemical getter 12 may be contained within a recess 13 provided in the inner surface of the glass substrate, such as the glass substrate 2. The chemical getter 12 may be used to absorb or bind with residual impurities after the chamber 6 is evacuated and sealed. The getter 12 may also be used to "sweep" the unit of gaseous impurities evolved during ambient weathering.

VIG units having a peripheral hermetic edge seal 4 (e.g., solder glass) are typically formed by depositing a frit or other suitable material (e.g., frit paste) on the periphery of the substrate 2 (or on the substrate 3). The glass frit slurry eventually forms the edge seal 4. The other substrate (e.g., substrate 3) is placed on substrate 2, then spacer/post 5 is sandwiched, and the glass frit is located between the two substrates 2, 3. The entire assembly, including the glass substrates 2, 3, spacers/pillars 5 and sealing material (e.g., a frit of a solution or paste), is then typically heated to at least about 500 ℃, at which point the frit melts, wets the surfaces of the glass substrates 2, 3, and ultimately forms a hermetic peripheral/edge seal 4.

After the edge seal 4 is formed between the substrates, a vacuum is drawn through the pump-out tube 8, forming a low pressure space/cavity 6 between the substrates 2, 3. The pressure in the space/chamber 6 may be brought to a level below atmospheric pressure by the evacuation process, e.g., below about 10-4 Torr. The low pressure in the space/cavity 6 is maintained and the substrates 2, 3 are hermetically sealed by means of an edge seal and a seal of the pump-out tube. Small high strength spacers/pillars 5 are arranged between the transparent glass substrates to keep the substantially parallel glass substrates separated from atmospheric pressure. As described above, when the space 6 between the substrates 2, 3 is evacuated, the pump-out tube 8 can be sealed by desoldering using a laser or the like.

High temperature bonding techniques, such as anodic bonding and frit bonding, as described above, are widely used methods to hermetically seal (e.g., form an edge seal) components made of silicon, ceramic, glass. The heating for the high temperature process is typically about 300-. The range of these prior art joining techniques generally requires a furnace body to be heated centrally, where the entire assembly (including the glass and any components within the glass housing) must be thermally balanced with the furnace to form a seal. Therefore, a relatively long time is required to achieve a desired seal. For example, as device size L increases, sealing time typically increases by L3. Furthermore, most temperature sensitive elements determine the maximum allowable temperature of the entire system. Therefore, high temperature sealing processes (e.g., anodic bonding and frit bonding) as described above are not suitable for fabricating thermally sensitive elements, such as tempered VIG units, and encapsulating sensitive elements, such as OLED devices. In the case of a tempered VIG unit, the thermally tempered glass substrate of the VIG unit will rapidly lose temper strength in a high temperature environment. In the case of the exemplary OLED encapsulation, the organic layer of a particular function will be destroyed at temperatures of 300-600 deg.C (and sometimes even as low as 100 deg.C). In the past, one approach to addressing this high temperature bulk sealing process was to develop a low temperature frit, but still use a bulk thermal equilibrium heating process.

According to the background art, a frit material and/or solder is typically a mixture of a glass material and a metal oxide. The glass composition may be tailored to match the Coefficient of Thermal Expansion (CTE) of the bonded substrates. Lead-based glass is the most common bonding/sealing material/technique and is widely used in Cathode Ray Tubes (CRTs), plasma displays, and VIG window units. The lead-based frit material is also a low permeability glass sealing material. Typically, solders are based on glassy materials and devitrification is prohibited.

The frit or solder is typically composed of a base glass, a refractory filler and a vehicle. The base glass forms a mass of frit or solder. The filler reduces the coefficient of thermal expansion to match the glass substrates to be bonded. This matching increases mechanical strength, reduces interfacial stress, and improves the crack resistance of the seal. The vehicle is typically made of a solvent (surfactant) that provides fluidity for screen printing (e.g., for dispensing into the gap to be sealed, and/or onto the surface to be sealed) and an organic binder.

The advantage of frit materials or solders of the above type is that they have relatively low melting points (e.g., in the range of about 480 ℃ -.

Many different types of commercially available glass frits have different melting points, coefficients of thermal expansion, adhesives, and screen printing properties. However, almost all low melting point formulations of frits or solders contain some lead. This may be a disadvantage, for example, the united states, european union and japan severely prohibit or limit the use of lead in the electronics manufacturing industry for the next few years. In the last few years, bismuth oxide based frits or solders have successfully replaced some lead based frits, but the melting temperature (Tg) of this type of frits is still higher than 450 ℃. Like lead-based frits, these bismuth oxide-based frits cannot be used to prepare temperature sensitive devices by existing furnace intensive heating processes. Low melting temperature (e.g., 375-. However, the wide use of these types of frits is limited. Furthermore, while the above-described frit materials have been improved over conventional methods, it is sometimes still difficult to meet the stringent thermo-mechanical requirements of low temperature for all glass peripheral seals. This is because low temperature glass solders are typically made of materials with large ionic radii and do not readily diffuse to the glass surface at low processing temperatures and times.

It would also be desirable to provide a VIG unit that is capable of surviving harsh environments, such as characterized by higher operating temperatures, and exposure to shock, vibration, humidity, contaminants, radiation, and/or the like. For example, the glass industry subject materials, the extreme use of which in harsh environments poses a threat to themselves. For example, skylights, glazing systems are subjected to extreme temperatures (150 ℃) and shock and vibration loads associated with wind loads. In fact, the ambient temperature near the VIG seal may exceed 150 ℃, with shock and vibration loads, and the ambient temperature of the building facade may be as high as 200 ℃. Therefore, it is difficult to provide an edge seal having long-term airtightness, mechanical strength, and a low heat conduction path.

Accordingly, there is a need in the art for a sealing treatment technique that does not involve heating the entire article being sealed to an elevated temperature, and/or a method of making the article.

According to an exemplary embodiment, a method of making a Vacuum Insulated Glass (VIG) window unit. The VIG unit assembly includes first and second glass substrates; a plurality of spacers for holding the first and second glass substrates; spaced from each other substantially parallel to each other; and edge sealing. The first glass substrate has an aperture formed therein, which can be used to evacuate a cavity defined between the first and second glass substrates. Forming a first multi-layer thin film coating on a portion of the first substrate that surrounds and/or is located on the inner diameter of the hole, the first multi-layer thin film coating comprising at least one metal-containing layer. Disposing a solid solder alloy pre-form within and/or around the hole, the solid solder alloy pre-form being in direct physical contact with at least a portion of the first multilayer thin film coating and comprising a metal. Disposing a sealing member on and/or within the hole such that at least a portion of the sealing member is in physical contact with the solid solder alloy pre-form. In making the VIG unit, a hermetic hole seal is formed by reactively reflowing the solid solder alloy pre-form to allow diffusion of material from the first multilayer thin film coating into the solder alloy material and vice versa.

According to an exemplary embodiment, the sealing member may have a second multi-layer thin film coating formed thereon, the first and second thin film coatings at least initially having the same thin film layers; and the solid solder alloy pre-form is in direct physical contact with at least a portion of the second multilayer thin film coating. The hermetic hole seal may also allow diffusion of material from the second multilayer thin film coating into the solder alloy material and vice versa when the VIG unit is manufactured.

According to an exemplary embodiment, the sealing member may be a plug inserted into the hole, a plate covering the hole, a plate having a plug protruding therefrom, the plate covering the hole and the plug extending into the hole. The sealing member may be formed of metal, metal alloy and/or glass.

According to an exemplary embodiment, the multi-layer thin film coating may metalize the substrate around and/or within the hole, and/or the sealing member. The multi-layer thin film coating may include a layer comprising nickel (e.g., a Ni/Ag/Ni layer stack, a Ni/Ag layer stack, a Si/Ni/Ag layer stack, and/or the like). The layer comprising nickel may be a layer comprising nickel chromium.

According to an exemplary embodiment, the solid solder alloy pre-form is formed from an indium silver alloy, SAC, Sn-Pb, SnBiAg, SATi or SATiRe. In other cases, the solid solder alloy pre-form may be based on tin and include at least one other material selected from the group consisting of: a late transition metal or metalloid; zintl anions from group 13, 14, 15 or 16; and a transition metal.

According to an exemplary embodiment, the hole seal may be formed while the VIG unit subassembly is held under vacuum. In some cases, the edge seal may be formed while the VIG unit subassembly is held at a first vacuum pressure, and the aperture seal may be formed while the VIG unit subassembly is held at a second vacuum pressure, the second vacuum pressure being lower than the first vacuum pressure.

According to an exemplary embodiment, the bore seal may be formed at a temperature of no more than 300 ℃, more preferably no more than 180 ℃ and sometimes no more than 160 ℃.

According to exemplary embodiments, the pump-out tube need not be desoldered or closed in the preparation of the VIG unit.

In exemplary embodiments, the VIG may be prepared using the methods described herein.

In an exemplary embodiment, a Vacuum Insulated Glass (VIG) unit includes: first and second substantially parallel spaced apart glass substrates, at least one of said first and second substrates being a heat treated glass substrate; a plurality of spacers disposed between the first and second substrates; sealing the edges; and a cavity at least partially defined by the first and second substrates and the edge seal, the cavity being evacuated to a pressure below atmospheric pressure. An aperture sealing member disposed within and/or over an aperture formed in the first substrate. The hole sealing member is used to evacuate the cavity during the VIG unit preparation process. The aperture sealing member and the first substrate are hermetically sealed from each other via an aperture seal formed by reactive reflow of a metal-containing solid solder alloy preform, causing (a) diffusion of material from a pre-configured first multi-layer thin film coating on the first substrate into the solder alloy material and vice versa, and (b) formation of an intermetallic compound (IMC) between an uppermost layer of the first multi-layer thin film coating and the reactive reflowed solder.

The features, aspects, advantages, and example embodiments described herein may be combined to realize further embodiments.

Drawings

The above and other features and advantages of the present invention will become more apparent and readily appreciated from the following detailed description of the exemplary embodiments of the invention, which proceeds with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a prior art vacuum IG unit;

FIG. 2 is a plan view of a bottom substrate, edge seal, and spacer of the Vacuum Insulating Glass (VIG) unit of FIG. 1 taken along the section lines shown in FIG. 1;

fig. 3 is a cross-sectional view of a VIG unit in accordance with an example embodiment;

FIG. 4 is an enlarged view of the end of FIG. 3 according to an exemplary embodiment;

FIG. 5 is an enlarged view of the metal layer stack disposed on the first substrate as shown in FIG. 4, in accordance with an exemplary embodiment;

FIG. 6 is a flowchart illustrating a process of preparing a VIG unit in accordance with an exemplary embodiment;

FIG. 7a is a graph of an exemplary temperature and pressure profile with respect to pumping that may be used in exemplary embodiments;

FIG. 7b is a chart of an exemplary temperature and clamp pressure sequence curve that may be used in exemplary embodiments;

fig. 8 a-8 b are cross-sectional microscopic images of exemplary SnAgCu metal seal structures;

fig. 9 is a schematic diagram illustrating an exemplary solder seal formation process in an exemplary embodiment;

FIG. 10 is a schematic illustration of an exemplary High Velocity Wire Combustion (HVWC) apparatus 1000 that may be used in exemplary embodiments;

FIG. 11 is an exemplary enlarged tip portion of an exemplary HVWC apparatus provided by Oerlikon Metco that may be used in exemplary embodiments;

FIG. 12 is a schematic diagram of a simulation showing the velocity of molten powder produced by feeder acceleration as it passes through the tip and exits the device of FIG. 10 toward the substrate;

fig. 13 is an enlarged view of a metal layer stack formed on a first substrate, which may be used in the example of fig. 3 and 4, according to an example embodiment;

FIG. 14 is another flowchart illustrating a process for preparing a VIG unit in accordance with an exemplary embodiment;

FIG. 15 is a graphical illustration of forces acting on a weld bead in an exemplary embodiment;

FIG. 16 is a graph illustrating movement of solder as a function of gap height in an exemplary embodiment;

FIG. 17 is a sequence of reactive reflow between solder and a metallized surface of glass in accordance with an exemplary embodiment;

FIG. 18 is an x-ray of a reflowed solder pre-form of a VIG with a controlled wetting front at a 90 degree bend made in accordance with exemplary embodiments;

FIG. 19 is a temperature profile of a reflow process that may be used in exemplary embodiments;

FIG. 20 is a schematic diagram of a metalized pump-out hole according to an exemplary embodiment;

FIG. 21 is a ring for holding a solder pre-form according to an exemplary embodiment;

FIG. 22 illustrates a feedthrough pump-out tool for a desoldering piston usable in exemplary embodiments;

FIG. 23 is a mechanical drawing of a high temperature (200 ℃) compatible linear vacuum feedthrough system with a bellows-assisted seal that may be used in exemplary embodiments;

FIG. 24 is a schematic view of a lid with a coil solder pre-form placed over and around a pump-out hole near a metalized area of a substrate according to an exemplary embodiment;

FIG. 25 is a schematic view of a solder pre-form inserted into a pump-out hole near a metalized inner edge of the pump-out hole in accordance with an exemplary embodiment;

FIG. 26 is a schematic view of a solder pre-form inserted into a pump-out hole near a metalized inner edge of the pump-out hole, according to an exemplary embodiment;

FIG. 27 shows an image of a solder bead formed by a metallized hole under vacuum;

FIG. 28 is a cross-sectional view showing the preform for indium silver during 4 minutes of reactive reflow at 140 ℃;

FIG. 29 is a cross-sectional view showing the preform for indium silver during 8 minutes of reactive reflow at 150 ℃;

fig. 30 is a high resolution XPS of an InAg IMC layer formed in an exemplary embodiment;

FIG. 31 shows experimental data for the change in tensile strength of a welded joint as a function of joint gap thickness;

FIG. 32 is an exemplary concentric tubular gap solderable contact usable in exemplary embodiments; and

FIG. 33 is an exemplary support fixture usable in exemplary embodiments.

Detailed Description

Example embodiments relate to a Vacuum Insulating Glass (VIG) unit having a metal-containing peripheral edge hermetic seal and/or a method of making the seal. The edge seal is formed when the metal solder pre-form alloy is reactively reflowed, wetting a metal coating that has been pre-coated on the perimeter of the glass substrate. The use of these techniques advantageously allows for lower processing temperatures, for example by careful selection of solder coating combinations. Advantageously, in exemplary embodiments, allows for the use of thermally tempered glass in VIG units without substantially sacrificing temper strength of the glass during manufacturing, allowing for the use of sputtered soft low-E coatings, thereby enabling the provision of thin film getter materials. In an exemplary embodiment, the vacuum may be advantageously formed without the use of a pump-out tube or the like.

More specifically, the exemplary embodiments use alloys based on tin, post-transition metals or metalloids from groups 13, 14, 15 or 16 and Zintl anions and transition metal dopants to form edge seals that (a) readily wet the coated glass, (b) have suitable rheological properties to form seals at temperatures that do not temper the glass and/or decompose the laminate, and/or (c) remain hermetic and have no porous structure in their volume. In an exemplary embodiment, a thin film coating on glass may work with tin-based intermetallic solders to form a robust hermetic interface. By appropriately energizing the seal, the presence of bubbles (e.g., microbubbles), voids, and/or other defects in the seal may be reduced. Since the process is a low temperature process, exemplary embodiments may use flexible and viscoelastic spacer (e.g., strut) technology based on naturally occurring layered polymer structures (e.g., of the de Gennes class).

One aspect of the exemplary embodiments relates to the development and use of a new alloy based on metals and metal solders that readily wet glass and have rheological properties sufficient to form a seal at temperatures that do not temper the glass and decompose the laminate, and the seal formed is hermetic, with no porous structure in its volume.

Another aspect of the exemplary embodiments relates to the development and use of thin film coatings or layer stacks disposed on glass substrates, together with solder, to form a robust sealing interface. The thin film coatings or layer stacks are preferably reactively wetted and intermixed via the metal solder in a very short time.

Another aspect of the exemplary embodiments relates to the development and use of electronic and/or radiative methods (e.g., radiant heating, forced convection heating, induction heating, and resistance heating, etc.) to energize the seal, potentially under vacuum, to form a bubble-free and defect-free uniform seal structure. The combination of methods to energize seal formation within a time that limits intermetallic compound (IMC) formation has been found to be advantageous for achieving and/or maintaining hermeticity.

Yet another aspect of still further exemplary embodiments relates to the development and use of flexible and viscoelastic spacer/strut technology, for example based on naturally occurring layered structures (e.g., de Gennes class).

In exemplary embodiments, these exemplary aspects may be combined in any suitable combination or sub-combination.

Preferably, exemplary embodiments may have a higher R value or a lower U value than is currently achievable, for example, because low temperature processes may cause flexible and thermally insulating spacers/pillars to be further spaced apart.

In an exemplary embodiment, the process comprises a sealing process, preferably no more than 350 ℃, more preferably no more than 300 ℃, and even more preferably no more than 250 ℃.

Referring now more particularly to the drawings, in which like reference numerals refer to like parts throughout the several views, FIG. 3 is a cross-sectional view of a VIG unit, according to an exemplary embodiment. It should be understood that the exemplary embodiment of fig. 3 is similar to the embodiment shown in fig. 1-2. For example, the first and second substrates (e.g., glass substrates) 2 and 3 are arranged substantially parallel to and spaced apart from each other. A plurality of spacers (e.g., posts or the like) 5 help to keep the first and second substrates 2 and 3 in this orientation. In the exemplary embodiment, a pump outlet 8 is provided; however, as will be described in greater detail below, the exemplary embodiment may also create a vacuum in the cavity 17 in the absence of the pump outlet 8.

The exemplary embodiment of fig. 3 differs from the VIG unit shown in fig. 1-2 by including an improved edge seal 15. More specifically, the improved edge seal 15 is formed when a metal solder pre-form alloy is reactively reflowed to wet a metal coating that has been pre-coated on the glass substrate (e.g., at the peripheral edge thereof). In this regard, fig. 4 is an enlarged view of the end of fig. 3 according to an exemplary embodiment. First and second metal layer stacks 19a and 19b are disposed on the first and second substrates 2 and 3, respectively. The solder preform is melted to form a ribbon of solder 23 containing a plurality of seals, at least volumetrically. The solder 23 is bonded to the first and second metal layer stacks 19a and 19b via first and second intermetallic compounds (IMCs)21a and 21b, respectively. As described below, the edge seal 15 can be formed under vacuum conditions and provide a good seal.

Fig. 5 is an enlarged view of the metal layer stack 19a disposed on the first substrate 2 as shown in fig. 4, according to an exemplary embodiment. As can be seen in the example of fig. 5, the first metal layer stack 19a comprises first and second nickel-containing layers 25 and 27 sandwiching a silver-based layer 29. The nickel-containing layers 25, 27 may include, consist essentially of, or consist of metallic Ni, NiCr, NiTi, NiV, NiW, and/or the like. In an exemplary embodiment, the composition of the first and second nickel containing layers 25 and 27 may be the same. The amount of nickel in each of the first and second nickel-containing layers 25 and 27 is preferably at least about 60%, more preferably at least about 70%, and even more preferably at least about 80%. Exemplary compositions include 80/20 and 90/10NiCr, NiTi, and the like.

The thin film layers shown in fig. 5 are formed by any suitable technique, such as e-beam deposition, sputtering, and/or the like. For example, the NiCr/Ag/NiCr layer stack may be formed by Physical Vapor Deposition (PVD), such as in an inert atmosphere comprising nitrogen, argon, and/or the like. It should also be appreciated that the exemplary layer stack may be selectively formed at the perimeter of the substrate using electrolytic techniques (e.g., techniques similar to those used in mirror image processing). In an exemplary embodiment, the presence of nickel may help provide good wettability while also acting as a diffusion barrier (e.g., capturing silicon, sodium, and/or the like from the underlying substrate) and forming a very strong nickel-silicide bond with the glass. It is understood that other metal layer stacks may be used in different related exemplary embodiments, for example, to match the contents of the solder material, and may be applied by any suitable technique.

The thickness of the layers 25 and 27 is preferably 10 nm to 5 micrometers, more preferably 20 nm to 3 micrometers, and still more preferably 50nm to 1 micrometer. The thickness of layer 29 is preferably 10 nm to 2 microns, more preferably 50nm to 1 micron, and even more preferably 100nm to 500nm or to 1 micron. The layer thickness of the NiCr/Ag/NiCr layer stack is 50nm, 100nm and 50nm respectively.

In the exemplary embodiment, although layers 25 and 27 are described as layers containing nickel, it should be understood that copper may be used instead of or in addition to nickel. It was found here that metal layers containing nickel and containing copper can adhere well to glass and match well with solder preforms based on tin, silver and copper alloys. Further details regarding exemplary solder pre-forms of exemplary embodiments are provided below. Although the exemplary embodiments are described in connection with wire preforming, other preforming (e.g., tape preforming) may be used instead of or in addition to wire preforming.

Fig. 6 shows a flow diagram of a process for preparing a VIG unit, according to an example embodiment. One or more preliminary operations may be performed in an exemplary embodiment (as shown in fig. 6). For example, the substrate may be cut and/or edge stitched at will. A hole for receiving the outlet of the pump, a getter retaining bag, and/or the like may be drilled. When a glass substrate is used, the substrate may be subjected to a thermal treatment (e.g., thermal strengthening and/or thermal tempering), chemical tempering, or the like. The heat treatment may be performed after cutting, drilling, and/or other operations. Thin films and/or other coatings may also be formed on the substrate. For example, low emissivity (low-E), anti-reflective, and/or other coatings may be formed on the substrate. The decorative coating may be screen printed, ink jet printed, and/or otherwise, in addition to, or as an alternative. In any case, if such a coating is heat treatable and the substrate needs to be heat treated, it may be coated on the substrate prior to heat treatment. If such a coating is not heat treatable and the substrate needs to be heat treated, it may be formed on a cut and/or otherwise processed substrate. If the substrate is not heat treated, the coating may be formed at any suitable time, e.g., may be coated and/or applied to the coating after cutting and/or other operations. Edge deletion may be performed if a coating or coatings are formed on the substrate, for example, in an area near an edge seal to be formed. The substrate may be cleaned (e.g., using DI water, plasma ashing, and/or the like). In an exemplary embodiment, the glass need not be pre-roughened and/or edge-deleted in the area near the edge seal to be formed.

Once the substrate is properly prepared and properly oriented, a metal coating (e.g., of the type described with reference to fig. 5) may be formed around the peripheral edge of the substrate, as shown in step S31 of fig. 6. As noted above, the substrate may be "nickel plated" or otherwise processed using any suitable technique. For example, localized PVD may be used to create a three-layer thin film coating having a layer comprising silver sandwiched between layers comprising nickel (e.g., NiCr), copper, and/or the like. The coating may be disposed on a peripheral edge of the substrate having a width at least as wide as the solder when melted.

As shown in step S33, a spacer may be disposed on the first substrate. The spacers may be substantially cylindrical struts, mat spacers, and/or the like. Which may be glass pillars formed from mica, polymers, laminated pillars, and/or any other suitable material or combination of materials. Septa are disclosed in U.S. patent No.6,946,171 and/or U.S. patent No.8,679,271. Each of which is incorporated herein by reference in its entirety. Here, because of the low temperature processes involved in the manufacture of VIG units, a wider range of materials may be provided for the spacer. Soft septa are less "burred" into the glass, and therefore generate less pressure (e.g., based on hertzian pressure) than harder objects. Thus, the struts or other structures may be spaced further apart. The function of using different materials for the spacers to space them further apart may advantageously improve the aesthetics of the unit and/or potentially reduce the thermal conductivity through the VIG unit.

Optionally, a getter material may be applied (e.g., in a preformed pocket, such as an over-coating, etc.). Getter materials and activation techniques are described, for example, in U.S. publication nos.2014/0037869,2014/0034218, and 2014/0037870, the entire contents of which are incorporated herein by reference. These and/or other getters may be used in exemplary embodiments. In an exemplary embodiment, a getter material, such as one containing barium and/or zirconium, may be coated on the substrate, such as by electron beam evaporation and/or the like. Because the coated getter is disposed over a large surface area, only a few angstroms of material may be required to perform a typical getter chemical gettering function. In an exemplary embodiment, the coating may be less than 20 angstroms, preferably less than 10 angstroms, and may be 5 angstroms or less. In this case, the getter may be continuously or discontinuously on the substrate. When a coated getter is provided, these materials are preferably applied before the formation of the metal coating associated with step S31.

In step S37, wire pre-forms or the like are arranged around the peripheral edge of the substrate. In an exemplary embodiment, the wire pre-form may be bent into a desired configuration in one or more steps not shown. Alternatively, the wire preform may be pieced together in a plurality of smaller sections. For example, the wires may be welded end-to-end, laser welded together, and/or the like.

As noted above, the solder pre-form may be an alloy of tin, silver and copper, and may also include tin, silver and copper. The solder pre-form is preferably lead-free. For example, SAC305, SAC0307, and/or the like may be used for example embodiments. SAC305 is a lead-free alloy containing 96.5% tin, 3% silver and 0.5% copper, and SAC0307 is a lead-free alloy containing 99% tin, 0.3% silver and 0.7% copper. In an exemplary embodiment, solder paste of the same or similar composition may be provided in place of or in addition to the wire pre-form.

It should be noted that SAC alloys with low silver content, such as SAC105, may be desirable in applications involving shock and vibration. However, in some cases, increasing the silver content helps to reduce the creep rate of SAC solders, thereby improving reliability under temperature aging and/or the like. Therefore, SAC alloys with high silver content, such as SAC405, may be desirable in high temperature applications. Alloys such as SAC305, SAC0307, etc. may be better "tempered" to provide desirable impact and vibration resistance while also providing good viability for many high temperature-related applications. Further, it should be noted that other alloys in the phase space around and/or between these eutectic alloys may be used in different exemplary embodiments.

In step S39, the sheets are arranged together and in step S41, a pump-out tube with melt is arranged in the pre-drilled hole.

Tape or other adhesive material may optionally be used to help secure the components together during further processing. Any polyimide, polyamide, acrylic, and/or other tape or adhesive material may be used to form the temporary seal. For example, Kapton, acrylate, and/or other tapes may be used in exemplary embodiments.

As shown in step S43, the sealing may be performed in vacuum. Sealing may include, for example, the process of heating to reflow the solder, applying static pressure during solidification of the joint (e.g., by mechanical clamping and/or the like), and the component being cooled and/or allowed to cool. In an exemplary embodiment, dynamic pressure may be used alternatively or additionally. The initial vacuum is preferably less than 1Torr, more preferably less than 0.5Torr, and sometimes less than 0.1 Torr. In exemplary embodiments, an initial inert gas environment may also be used in connection with such operations.

The heating may be performed at an elevated temperature sufficient to reflow the solder, but preferably no more than 390 c, preferably no more than 350 c, preferably no more than 300 c. Sometimes not exceeding 240-. In an exemplary embodiment, the peak temperature is just above the contour temperature of the solder. For example, in the exemplary embodiment, the peak temperature is preferably less than 50 ℃ above the contour temperature, and more preferably 20-40 ℃ above the contour temperature. For example, the peak temperature may be about 40 ℃ higher than the contour temperature, and in some cases may be about 240 ℃ and 250 ℃. Heating may be performed for several minutes to several hours. It is preferably heated for 1 minute to 2 hours, preferably 5to 60 minutes, and sometimes 10 to 30 minutes.

Reflow of the solder may generate bubbles. These bubbles can become trapped in the edge seal and degrade the seal quality (e.g., by compromising its structural integrity and sealing performance) by, for example, leaving voids and/or the like in the fired seal. However, heating under vacuum conditions is advantageous to solve these problems. E.g. in vacuumHeating under conditions essentially aids in the aspiration of bubbles during reflow. In this regard, fig. 8 a-8 b are cross-sectional microscopic images illustrating an exemplary SnAgCu metal seal structure. In particular, FIG. 8a clearly shows that up to 10^-2The existence of voids after partial vacuum of Torr. In contrast, fig. 8b shows that when the seal is fully formed and the VIG unit is in full vacuum, there are no significant voids. Although vacuum heating is preferred, an inert gas atmosphere may also be used during reflow.

A wire having a width of about 1 mm may be expanded (e.g., to 10 mm or even more in some cases). The nickel in the metal plating diffuses into the solder and vice versa. Thus, in the exemplary embodiment the reflow process is reactive, such that some layers of material are created that make up the hermetic seal, and these layers are found to be very smooth. A new phase of nickel is generated. The bottom layer of material in the metal layer stack closest to the nickel is generally characterized as (Ni)_xCu_1-x)₃Sn₄The top layer of SAC solder closest to reflow is generally characterized as (Cu)_yNi_1-y)₆Sn₅. The IMC layers 21a and 21b in fig. 4 may include at least these two layers in an exemplary embodiment. In an exemplary embodiment, glass/NiCr/Ag/NiCr/SnAg is included_3％Cu_0.5％The layer stack of (a) as shown in fig. 5, may be transformed to comprise glass/NiCrO_x:Si/(Ni_xCu_1-x)₃Sn₄/(Cu_yNi_1-y)₆Sn₅Layer stack of/SAC. In other words, in exemplary embodiments, first and second metal layer stacks 19a and 19b may be transitioned from a NiCr/Ag/NiCr layer stack to include NiCrO_xA layer of Si, such as silicon, is leached from the underlying substrate and/or oxygen enters during pumping. It should be noted that in exemplary embodiments, the seal improves thermal cracking between the glass substrates, thus facilitating a reduction in thermal conductivity.

The pumping may be performed in step S45, for example using a pumping tube. In an exemplary embodiment, the pressure within the cavity may be pumped to 10^-6And (5) Torr. In other exemplary embodiments, pumping may be accomplished without the use of a tube.FIG. 7a is a graph of an exemplary temperature and pressure profile with respect to pumping that may be used in exemplary embodiments. In the example of fig. 7a, the pressure inside the component is measured. As shown in fig. 7a, the peak temperature is slightly above the contour temperature. The pressure may decrease rapidly, but in some cases the pressure may increase slowly thereafter and decrease slowly, for example, as bubble formation and venting occur. In some cases, a disturbance may occur and diminish rapidly. It should be understood that other temperature and/or pressure profiles within the component may be used in different exemplary embodiments, and that what is shown in FIG. 7a is an example only. FIG. 7b is a chart of an exemplary temperature and clamp pressure sequence curve that may be used in exemplary embodiments. It should be appreciated that other temperature and/or clamp pressure profiles may be used in different exemplary embodiments.

When the tube is configured, the tube may be sealed in step S47. This can be accomplished using pump-out tube desoldering techniques, which are described in U.S. patent nos. 8,742,287; U.S. patent nos. 8,742,287; and/or U.S. publication No.2014/0087099, the entire contents of each of which are incorporated herein by reference.

When a getter is provided in the pouch, the getter may then be activated, as shown in step S49. Alternatively, or in addition, when the substrate is coated with a getter, the heat associated with the seal may be sufficient to activate the getter.

It should be noted that the chamber may be cleaned in conjunction with plasma enhanced evacuation techniques and static plasma grids or arrays, for example, as set forth in U.S. publication No.2012/0304696, which is incorporated herein by reference in its entirety. Ozone cleaning techniques may also be used, for example, as described in U.S. publication No.2013/0292000, which is incorporated herein by reference in its entirety.

The pump-out tube may have an optional protective cap thereon, for example, as described in step S51. Various techniques may be used herein for protecting the pump-out tube and for the exemplary embodiments. See, for example, U.S. patent No.8,833,105 and U.S. publication nos.2013/0074445,2013/0302542,2013/0306222, and 2013/0309425, the entire contents of each of which are incorporated herein by reference.

In an exemplary embodiment, an optional secondary, non-sealing peripheral seal may be provided. In an exemplary embodiment, the seal may be a peripheral polymer seal, and it may comprise, for example, silicon, polyamide, PIB, and/or the like. In some cases, it may help protect the hermetic edge seal of at least a portion of the package.

When tempered glass is used, it is preferred that at least 70% of the temper strength be retained in the finished VIG unit, and more preferably at least 75% of the temper strength be retained in the finished VIG unit. More preferably, at least 85% of the temper strength is left in the finished VIG unit, and more preferably at least 95% of the temper strength is left in the finished VIG unit.

Fig. 9 is a schematic diagram illustrating an exemplary solder seal formation process in an exemplary embodiment. As shown in fig. 9, a component with a solid solder preform sandwiched between thin film coatings supported by opposing first and second substrates is inserted into an inert atmosphere and/or low vacuum environment. Since the preformation temperature of the solder is less than the melting temperature, the solder preform is depinned. However, as the temperature increases and the temperature is about the pre-melting temperature of the solder, reactive reflow begins. Voids, bubbles, etc. are formed in the liquid or liquid solder and the thin film coating begins to dissolve into the solder and vice versa. The component is moved into a vacuum state and the temperature exceeds the melting temperature of the solder. The gas bubbles in the liquid solder are largely removed from the solder, for example, in a vacuum reflow operation. The thin film coating diffuses into the solder and vice versa. The thin film coating may also be at least partially dissolved into the substrate and vice versa. The solder is cooled and/or allowed to cool under high vacuum and the temperature returns to room temperature, completing the formation of the hermetic seal. Of course, it should be understood that while static and/or dynamic pressure applications are not shown in fig. 9, they may be used in this example process. It should furthermore be understood that it is only one schematic illustration of how the sealing operation is performed and that other processes may be used instead of the exemplary process shown in fig. 9.

It should be appreciated that the exemplary embodiments described above relate to coating glass surfaces by Metal Layer Stacks (MLSs). The solder joint generation technique of the exemplary embodiments involves an intermetallic reaction of the MLS and the surface of the solder mass to create a strong bond and form a thin metallic interlayer during solder reflow. The intermetallic layer is stronger than the bulk solder, but more brittle. Therefore, an interfacial IMC layer with too large a thickness is considered unreliable under mechanical stress. It has been found that the diffusion rate is faster at higher temperatures and the growth rate of the interfacial intermetallic layer at the interface increases over time. However, in some cases, the reliability of the solder at high temperatures may be improved by inhibiting the growth of intermetallic layers under the metal layer stack interface. The following paragraphs are provided to illustrate the growth of the IMC layer and to illustrate factors and the like that may be used to adjust the growth of the IMC layer to produce a high quality seal in some instances.

The thickness of the IMC layer may depend on factors such as temperature, time, solder volume, solder alloy properties, plating morphology, and the like. The intermetallic layer grows with time and at high temperatures it grows faster. Maintaining the peak temperature for a longer period of time during reflow increases the initial intermetallic layer thickness and changes its morphology. Thus, shorter peak temperatures may be advantageous in some situations.

Intermetallic layers may grow out of the failure sites, these failure sites may move to the interfacial intermetallic layer, in some cases possibly due to the weaker interface between the intermetallic layer and the bulk solder, and the high elastic modulus of the intermetallic compound increases the stress of these layers. During the high temperature aging process, voids are generated due to tin diffusion from the interface, and thus the strength of the joint is reduced. Silver-related intermetallic layers, such as Ag3Sn, may be formed in the bulk solder and migrate over time to the interface. Increasing the concentration of silver in the solder alloy can produce larger flakes of Ag3Sn and larger needles in the bulk solder, which tend to be brittle and can initiate breakage. Thus, the amount of silver can be adjusted to provide a better long term seal. In some cases, solder joints with less than 3.5 wt.% silver may reduce large Ag₃Formation of Sn intermetallic layer. In some cases, solder alloy compositions having less than 1.2 wt.% silver have a seal qualityAnd (4) the advantages are achieved.

In addition, the intermetallic growth rate of the solid-liquid couple is much faster than that of the solid-solid couple. Thus, as noted above, it may be more advantageous to use solid pre-forms. Other properties, like intermetallic layer roughness, can have an effect on the seal quality. For example, as the thickness of the intermetallic layer increases, there is a tendency for roughness to increase, which in some cases can lead to cracking failure. It has been found that if the surface roughness is reduced, a less brittle intermetallic layer can be formed.

In an exemplary embodiment, a small amount of nickel is introduced into a lead-free solder containing tin and copper to improve fluidity. Nickel can be used to create perturbations in the crystal structure and can promote early nucleation of intermetallic phases during the welding process. This in turn can help provide better flow and bright solder pieces. Nickel modified SnCu and the like may also reduce interfacial intermetallic growth. Doping with trace rare earth elements may also be useful in these and/or other respects. For example, cobalt, nickel, antimony, and/or the like may produce a thick initial intermetallic layer after reflow that acts as a diffusion barrier but hinders subsequent growth of the intermetallic layer.

While the exemplary embodiments described with respect to SAC have described alloys, it should be understood that Zintl materials may also be used. Zintl materials include late transition metals or metalloids of group 1 (alkali metals) or group 2 (alkaline earth metals) and group 13, 14, 15 or 16. Furthermore, the exemplary embodiments may include any suitable alloy based on TiN, including Zintl materials and/or anions. Similarly, while exemplary embodiments have been described in SAC-related alloys, other metal alloys and transition elements based on post-transition metals or metalloids in groups 13, 14, 15, or 16 may also be used. For example, exemplary embodiments may include a metal alloy preform based on an intermetallic compound of tin and one or more additional materials selected from post-transition metals or metalloids; zintl anions selected from groups 13, 14, 15 or 16 (e.g., In, Bi, etc.); and transition metals (e.g., Cu, Ag, Ni, etc.); and does not include Pb. Other materials such as In, In and Ag, Bi and In, etc. may be included. In general, any indium alloy material (e.g., sold by indium tin corporation) may be used in the exemplary embodiments. Lead-free substances may be preferred for the reasons mentioned above. In an exemplary embodiment, other non-tin-based materials (e.g., based on some other metallic material) may be used.

As noted above, it is understood that a fully tempered VIG unit may be prepared using a metal seal formed based on a hermetic solder/metal layer/glass joint. In some cases, the quality of the hermetic seal, and even the presence of the seal, depends to a large extent on the metal layer precoated on the periphery of the glass. The entire thin film stack can be formed using MSVD engineering, which can help provide the following stack: (i) has very low porosity and high density close to bulk material, (ii) is highly adherent to glass, (iii) includes low or even almost no stress. And (iv) has a higher threshold energy release rate.

MSVD engineering is advantageous in some cases because it can provide the above listed properties for the above stack. However, it is preferable to increase the deposition rate and/or simplify the deposition process. For example, since the hermetic seal is only disposed at the peripheral edge of the substrate, a deposition mask may be required to leave the center of the glass uncoated. However, this masking process is still cumbersome, such as having to deposit and remove a mask, which may require many deposition, cleaning, and/or other steps, thereby slowing the overall process. In fact, it is preferable to achieve "on-line" processing speeds, e.g., "line scans" of about 1 meter per second.

Accordingly, exemplary embodiments perform a selective deposition process to allow for the formation of a metal stack on selective regions of the glass. In this regard, exemplary embodiments provide a method for selective metal deposition of glass by activated high energy spray deposition or activated high energy nano-spray deposition. More specifically, the exemplary embodiments implement a High Velocity Wire Combustion (HVWC) technique or a high velocity oxy-fuel (HVOF) technique. Although wire flame spraying is a relatively old thermal spray process, modern equipment allows the production of high quality coatings with good uniformity, high density and low roughness, for example, due to increased particle velocity as a result of increased combustion gas velocity. For example, the spray particles may be accelerated to velocities in excess of 250 m/s, for example, when the wire is sufficiently atomized may be combined with HVWC technology. For HVOF, the particle velocity impinging on the substrate is preferably greater than the speed of sound, more preferably Mach 2 or greater, more preferably Mach 4 or greater. The combustion wire thermal spray process of the exemplary embodiments generally involves spraying molten metal onto a surface to provide a coating. The wire-like material is continuously fed in a very hot combustion zone and melted in a flame (e.g., oxy-acetylene flame, hydrogen and oxygen mixture to provide a reducing atmosphere and/or the like), and atomized using compressed air or nitrogen to form a fine spray. For HVWC and HVOF techniques, wire-like metals and/or alloys can be used as the spray material and a combustion flame or electric arc can be used as its heat source. As will be described in greater detail below, Ni, NiCr, Ag, and/or other wires may be used to form the metallic coating of the exemplary embodiments.

In HVWC and HVOF techniques compressed air and/or inert gas surrounds the flame and atomizes the molten tip of the wire. This helps to accelerate the spray of the molten particles against the pre-cleaned surface of the substrate, which in an exemplary embodiment may be located approximately 12-14 inches from the end of the flame. In terms of accelerated blasting, the process gas may include helium, nitrogen, argon, oxygen, and/or the like. Nitrogen may be advantageous when precipitating metals because nitrogen generally helps to prevent oxidation and is less expensive than helium. However, other gases may be used to deposit silver and/or nickel chromium, as nitrogen generally promotes nitride formation. Helium has been found to be a good process gas for producing high quality coatings in the context of efficient processing. This is because helium can achieve the highest gas velocity. The deposition may be performed in a helium-containing atmosphere that allows for gas recirculation, for example, to save costs.

In HVWC and HVOF techniques, fine droplets quickly solidify to form a coating when the spray contacts the surface of the substrate being prepared. The spray coating is ultra-fine crystalline due to the rapid solidification process. In an exemplary embodiment, the substrate may be heated to a base temperature between 80-150 ℃. Preferably the temperature is below 390 c, more preferably below 300 c, and in some cases the temperature may be 100 c or less. In some cases, higher temperatures in the above and/or other ranges may be desirable, for example, to help degas the substrate surface and/or remove physisorbed and/or chemisorbed water from the substrate; however. Too high a temperature may cause unnecessary de-tempering, melting, bending, or the like of the tempered glass substrate, and therefore the selection of the temperature and/or the temperature distribution should be noted. This temperature range allows the metal spray droplets to wet after reaching the surface. In addition, the particles that affect the substrate exceed the threshold (critical) velocity of the powder and substrate combination, causing them to deform and bond in the dense layer. As the process continues, the particles continue to affect the substrate and form bonds with previously deposited materials, resulting in a uniform deposition with less porosity and higher bond strength. Advantageously, this temperature range helps to avoid metal oxidation, does not cause significant de-tempering, etc.

Also, as will be seen from the more detailed description below, this technique advantageously allows a wide variety of metals to be deposited directly onto glass as a metal stack at temperatures that do not compromise the integrity and strength of the glass. For example, for atomized materials generated from feedstock, the temperature of the powder gas jet and the temperature of the powder material are preferably low enough to prevent phase changes and the accumulation of significant stress in the deposition and/or substrate. The properties of the film can be modified by changing the feed rate of the raw materials, the gas flow rate, etc., to form a gradient layer. The presence of a graded layer may be advantageous when the solder reflows, as the presence of the pores helps to localize the extent of the reflow and thus local wetting of the solder.

In the HVWC and HVOF techniques, the particles impacting the glass and forming the coating may be in the form of a nanopowder, e.g. having a particle size distribution in diameter or main distance of less than 500nm, preferably less than 250 nm. More preferably less than 100 nm. In exemplary embodiments, particles having a sub-micron size distribution, which may be as low as 40-100nm in diameter or major distance, may be used to form the coating.

For HVOF technology, the metal powder may replace or supplement the wire feedstock. For example, the initial particle size range of the metal powder may be: the diameter or major distance ranges from 10 nanometers to less than 10 micrometers, preferably from 25 nanometers to 1 micrometer or less, and sometimes from 40 or 50 micrometers to 0.5 micrometers. In an exemplary embodiment, the particles may be ejected onto the substrate at high speed using a plasma jet in an inert atmosphere. In an exemplary embodiment, these powders may be accelerated by injecting a high velocity stream of inert gas. In the latter case, the high velocity gas stream may be generated by expansion of a pressurized preheated gas through a nozzle. The pressurized gas can expand to achieve high velocity while reducing pressure and temperature. The powder particles are initially carried by a separate gas stream and may be injected into the nozzle at a lower pressure point at or downstream of the nozzle inlet. The primary nozzle gas flow may accelerate the movement of particles and affect the substrate surface after exiting the nozzle.

In HVOF and HVWC techniques, filters may be used in order to ensure that particles of the largest desired size are emitted towards the substrate. Filters may be used to help ensure that more uniformly sized particles condense on the glass surface. When the particles are charged, either intentionally or as a result of the deposition technique used, then electromagnetic filters or the like may be used in this regard. For example, the electromagnetic filter may help evaporate substances and/or re-vaporize larger nanoparticles that exceed a certain size threshold. The electromagnetic filter may also be advantageous to help at least partially ionize the particles so that they adhere better to the substrate surface. Strong magnetic fields can be used for these purposes. For example, it is preferable to use a magnetic field of at least 5milliTesla, that is, a magnetic field of up to several hundred milliTesla (1000milliTesla or less).

The HVWC and HVOF flame spray processes of the exemplary embodiments can be performed in the exemplary embodiments with vertically-standing substrates. For example, exemplary embodiments may use a gun-like nozzle or the like that may be automatically moved across the substrate by an XY plotter platform, robotic arm, or the like. A nozzle hood with a variable aperture may be used that allows for selective deposition of the coating on a variety of sizes of desired areas. In an exemplary embodiment, baffles may be used inside the device to help capture the reflected particulate matter.

FIG. 10 is a schematic illustration of an exemplary high-velocity-line combustion HVWC apparatus 1000 that can be used in exemplary embodiments. As shown in fig. 10, the device 1000 receives wire 1002 from a wire source 1004 into the body portion. The first set of inlets 1006a and 1006b contain a carrier gas and the second set of inlets 1008a and 1008b contain an oxygen and fuel mixture. The shield 1010 is used to house the device 1000, provide cooling, reduce the incidence of spray in unwanted directions, and the like. The molten particles 1012 are accelerated toward the substrate and form 1014 and a coating 1016 thereon. FIG. 11 is an exemplary enlarged tip portion of an exemplary HVWC apparatus provided by Oerlikon Metco, usable in exemplary embodiments, which may be used in exemplary embodiments, wherein 1102 denotes wires, rods; 1104a and 1104b represent oxygen; 1106a and 1106b represent fuel gas; 1108 denotes a nozzle; 1110 denotes an air cap; 1112 denotes a spray flow; 1114 denotes a substrate; 1116 represents spray attachment; reference numeral 1118 denotes air. In this regard, the multicoat advanced automated line combustion spray system Oerlikon Metco can also be used in the exemplary embodiments. FIG. 12 is a schematic diagram of a simulation showing the velocity of molten powder produced by feeder acceleration as it exits the apparatus of FIG. 10 through the tip and toward the substrate, where 1202 represents an adjustment lever; 1204 denotes a contact; 1206 denotes a needle.

In both HVWC and HVOF techniques, molten material is sprayed onto the surface of an object to form a continuous, pinhole-free coating. The sprayed glass substrate is exposed to a plume of hot metal particles. As described above, the substrate and the plating layer are not adversely affected by high temperatures. Which advantageously helps provide dimensional and morphological stability, with little or no cracking, no reduction in adhesion strength, and/or the like.

HVOF and HVWC techniques can be advantageously used to create individual layers and entire layer stacks having desired thickness uniformity, porosity, and other properties. Since the layers formed in this manner are dense and robust, a bilayer stack may be used in exemplary embodiments to metalize the periphery of the edge seal. The bilayer stack can be selectively deposited under atmospheric conditions (e.g., in a reducing atmosphere), but is still highly adherent to glass, dense, and low in oxidation. When a solder preform of the type described herein is reflowed between two such coatings on adjacent glass substrates, a hermetic seal can be formed under ambient or vacuum conditions. In exemplary embodiments, the dual layer coating may be polished or lapped using an ultra fine carbide surface abrasive to remove unwanted oxide scale (e.g., in the upper layer) prior to forming the IMC.

The bilayer stack of the exemplary embodiments includes a nickel-containing layer formed directly or indirectly on a substrate. The nickel-containing layer may be made of metal Ni, NiCr, NiTi, NiV, NiW, and/or the like. A layer comprising silver may be disposed on and in contact with the layer comprising nickel. These layers may be formed by HVWC or HVOF techniques, for example, which are selectively deposited to metallize the peripheral edge of the substrate. These layers may be formed using any combination of HVWC and HVOF techniques (e.g., two layers may be deposited using HVOF or HVWC techniques, HVOF techniques may be used to deposit one layer, HVOF techniques may be used to deposit the other layer, etc.).

As described above, in exemplary embodiments, a selective polishing process may be used to remove oxide scale from the bilayer stack. The oxide and/or nitride content of the layer and/or stack is preferably equal to or less than 10 wt.%, more preferably equal to or less than 5 wt.%, and even more preferably equal to or less than 1 or 2 wt.%. The coating is preferably carbon-free, or at least substantially carbon-free. This can be a concern, for example, when combustion gases are used in HVOF technology. Preferably, the carbon content is less than 2 wt.%, more preferably less than 1 wt.%, and sometimes less than 0.5 wt.%, for individual layers and/or for the entire layer stack (e.g., after selective polishing).

The thickness of the nickel-containing layer is preferably 5-20 microns, more preferably 10-20 microns, and the nominal thickness is 15 microns. The thickness of the silver containing layer is preferably 15-25 microns with a nominal thickness of 25 microns. Thus, the thickness of the entire bilayer stack may be 20-45 microns, for example, with a nominal thickness of 35 microns. The thickness of each layer containing nickel and containing silver preferably varies by no more than 15%, more preferably no more than 10%, and sometimes no more than 5%. The thickness of the entire bilayer stack preferably varies by no more than 40%, and more preferably by no more than 30%.

The RMS roughness (Ra) of the nickel-containing layer is preferably less than 2 microns, more preferably less than 1 micron. The RMS roughness (Ra) of the silver-containing layer is preferably less than 2 microns, more preferably less than 1 micron, and even more preferably less than 0.5 micron. After polishing, the RMS roughness (Ra) of the bilayer stack is preferably less than 2 microns, more preferably less than 1 micron. In some cases, HVWC techniques may provide better (i.e., lower) RMS roughness (Ra) values.

In an exemplary embodiment, metallic solder paste may be used to "fill" into the asperities to bring the surface roughness above a desired level. The paste may have the same composition as the solder used or a similar composition. Alternatively, or in addition, the solder may be melted to the coating surface prior to IMC formation, for example to ensure that the solder is filled to any potential leak paths, and may be plugged using this technique.

The porosity of each layer and the entire stack of layers is preferably less than 10%, more preferably less than 5%, and sometimes less than 2%, e.g. vol.%. HVWC technology may provide better (i.e., lower) porosity values in some cases.

In some cases, the bonding or bond strength of each layer and the entire layer may be in the range of 2 to 50 MPa. For example, layers containing nickel and silver having an adhesion or bonding strength of 10MPa may be formed, and a two-layer stack having an adhesion or bonding strength of 20MPa may also be formed. In some cases, the bond strength may be higher when using HVOF techniques. The bond is preferably strong enough that the failure mode involves breaking of the glass, not the seal.

It was found that a layer comprising nickel arranged at the bottom of the bilayer stack is advantageous for adhesion, especially when formed on the air side of the glass. That is, the layer containing nickel forms a silicide with the glass, thereby promoting adhesion. When a layer containing nickel is formed on the tin side of the glass, adhesion may be poor, as the presence of "extra tin" may hinder the formation of silicides used to promote adhesion. Thus, when the tin side of the glass is coated, exemplary embodiments may form a silicon-containing layer on the tin side of the substrate prior to deposition of the bilayer stack. The silicon-containing layer may be coated on the substrate (e.g., by sputtering, etc.) or otherwise formed on the substrate at least in the areas where metallization occurs. The silicon-containing layer may be a layer containing silicon oxide, silicon nitride, silicon oxynitride, the like, or may include silicon oxide, silicon nitride, silicon oxide, or the like. Local ion beam cleaning may be used in place of or in addition to the formation of the selective silicon-containing layer, for example, to help pre-treat the tin side of the glass.

As described above, HVWC technology can accept feedlines of Ni, NiCr, Ag, and/or similar materials. The gas may comprise hydrogen and/or oxygen, with a hydrogen to oxygen ratio in the range of 01: 1to 02: 1, even higher, e.g., an exemplary ratio of 1.2: 1. the flame temperature may be in the range of 2800 ℃ and 3500 ℃, for example, the operating temperature may be about 3300 ℃. The particle velocity is preferably at least 150 m/s, more preferably at least about 200 or 250 m/s. In some cases, the particle velocity may accelerate to 400 meters/second or even higher. In some cases, these engineering conditions may result in a Dynamic Deposition Rate (DDR) of 10g/min to 1000g/min (e.g., DDR of 100 g/min).

Fig. 13 is an enlarged view of a metal layer stack formed on a first substrate, which may be used in the examples of fig. 3 and 4, according to an example embodiment. Here, fig. 13 is similar to fig. 5, showing a metal layer stack 19 a' that may be used to improve the edge seal (e.g., 15 in fig. 3-4). Unlike fig. 5, however, the metal layer stack 19 a' of fig. 13 does not have a nickel-containing layer disposed over the silver-containing layer 29. In contrast, the first nickel-containing layer 25 is disposed directly or indirectly on the surface of the substrate 2, while the silver-containing layer 29 is disposed on and in contact with the first nickel-containing layer 25. As shown in fig. 13, an optional silicon-containing layer 26 is provided to promote adhesion between the first nickel-containing layer 25 and the surface of the substrate 2 (e.g., when the metal layer stack 19 a' is disposed on the tin side of the substrate 2). The silicon containing layer 26 is selective and may not be required, for example, the first nickel containing layer 25 is disposed directly on the air side of the glass.

Although the layer stack 19 a' is shown only on the first substrate 2, it is to be understood that it can also be used for both substrates. Solder pre-forms may be placed on the layer stack 19 a' and an IMC may be formed as described above.

Fig. 14 is another flowchart illustrating a process of preparing a VIG unit in accordance with an example embodiment. Fig. 14 is similar to fig. 6. However, fig. 14 differs in that the metal coating of fig. 13 is formed on the substrate in step S31' (e.g., using HVOF or HVWC techniques), and the formed coating may be selectively polished in step S32. As described above, the coating may be formed in an atmosphere and/or a partially reducing atmosphere. The metallic coating has desirable porosity, thickness uniformity, and adhesion, for example, when the above layers are formed using HVOF or HVWC techniques.

In an exemplary embodiment, HVOF/HVWC deposition may occur immediately thereafter (e.g., within seconds or minutes, and possibly no more than 1 hour, preferably no more than 30 minutes, and more preferably no more than 15 minutes) when the substrate of the VIG has been cooled to a temperature below 390 ℃, for example, as described above, which helps to reduce the risk of water re-adsorption onto and into the glass. In this regard, two thermally degassed glass substrates generally provide a better vacuum for a longer period of time. In principle, this approach may help to produce a VIG that releases gas that decreases over time (e.g., where all other factors are equal).

Although exemplary embodiments are described in connection with SAC alloys, exemplary embodiments may use InAg solder alloy pre-forms and/or the like. In exemplary embodiments, InAg materials may facilitate the formation of different, yet effective, IMCs that provide a desired level of hermeticity for the edge seal.

It should be understood that the techniques described herein may be used to seal the pump-out holes instead of or in addition to the edges of the VIGs. For example, exemplary embodiments may use techniques similar to those described above to make a strong, tubeless seal around a pump-out hole at temperatures below 300 ℃, 180 ℃, and 350 ℃. A heat treated (e.g., thermally tempered) substrate may be used and is preferably not de-tempered. Prepared by elaborate leak test units and recorded to have a leak rate of less than 10 after exposure to the environment^-13atm cc/s. The seal of the pump-out tube is preferably gas-tight and the sealing time is relatively long (e.g., 20 years or more). The secondary polymer seal can be usedThe service life is prolonged.

Exemplary embodiments achieve a robust hermetic seal under thermo-compression conditions by using a metallic solder (e.g., indium and indium silver alloy, SAC, Sn-Pb, SnBiAg, SATi, SATiRE, and/or the like). As mentioned above, this technique is based on the local modification of the glass surface around the pump-out hole, with a highly adhesive metal coating, selectively modifying the surface properties of the glass so as to have a wettability with respect to the metal solder used, for example similar to the technique disclosed above. The greater contrast in the solder contact angle between the uncoated (thetas) and coated (thetas) areas helps to confine the liquid solder to the more wettable areas. This effect is also in some cases more pronounced by the reactive reflow process, i.e. the diffusion of the solder into the metal coating to form the IMC.

In an exemplary embodiment, a peripheral seal between two glass sheets may be formed by using a low temperature glass solder or metal solder system, followed by pumping, gas purging, plasma cleaning, and final evacuation. The partial peel seal may then be subjected to VIG sealing at a reflow temperature of 160 ℃ or less. This sequence may involve two different temperatures in some cases, advantageously simplifying the manufacturing process and allowing the peripheral seal to be completed for the first time at ambient pressure (although in vacuum or reduced oxygen or inert atmosphere), while the desoldering masking seal may be performed under high vacuum. In exemplary embodiments, different reflow engineering and/or engineering temperatures may be used for different seals, such as when using metal seals to form the edge seal and the pump-out hole. It should be appreciated that a two step engineering may allow for a helium leak check of the peripheral seal prior to forming the desoldering seal. It is also possible to use the same solder and to simultaneously complete the peripheral and desoldering seals, for example under high vacuum.

The desoldering seal may be formed by a metal rivet plug in a metal pump hole, abutting a metalized cover plate (or sheet metal, stainless steel, nickel, copper, and/or the like) to the pump-out region of the VIG. Some example embodiments may use a flat glass cover, a metalized or metal cover, and/or a secondary metal solder.

Advantageously, these exemplary methods are compatible with the layering process, thereby allowing VIGs to be layered from either side of the unit.

The exemplary embodiment forms a "true seal" rather than simply using a "gasket". In this regard, the true seal forms a chemical bond at the mating surface, while the gasket forms only a vacuum tight barrier. The chemical bonding associated with a true seal may be achieved by a reaction occurring between the metal solder preform and the metallized glass surface (or thin metal sheet) to produce an alloy layer or intermetallic layer or compound (IML) and/or by oxidative bonding. Here, when the fresh, unoxidized surface of the metal comes into contact with oxides (such as glass and ceramics), oxidative bonding may occur due to rapid oxidation of the soft metal. Exemplary embodiments include the former type of seal, which has been found to maintain a stable gas seal over an extended period of time. In this regard, forming seals of the former type may reduce the risk of unwanted oxide formation by processing in a vacuum or inert or low partial pressure oxygen environment, and/or provide a means for removing the oxide with a getter. Exemplary embodiments relate to processing in ambient atmosphere, but scavenger-like elements may be used to remove the lean oxides, such as described below.

Advantageously, exemplary embodiments can avoid the formation of solidification defects to achieve a stable and reliable joint/seal. In this regard, exemplary embodiments advantageously reduce the likelihood of defect generation, such as delamination, cavity shrinkage, rough dendritic surfaces, voids, and/or other defects. These defects may be caused by a variety of factors such as local delay in solidification, undercooling, microphase segregation, gas evolution, solidification shrinkage, and the like. These defects are due to poor solder compatibility with the plating material and thermal mismatch of the solder with other materials such as glass. However, the exemplary embodiments use compatible materials that facilitate forming a hermetic seal on a VIG scale. In addition, long-fingered solidified solder flakes are present near the periphery of some fabricated metal-sealed VIGs, and these defects are due to the molten solder flowing and solidifying toward the glass interior region. Also, example embodiments may reduce the likelihood of such defects occurring in a VIG.

In an exemplary embodiment, a uniform and hermetic gap is maintained when the solder preform is sandwiched between the glass sheets prior to reflow. The initial thickness or height of the preform is calculated based on factors such as cost, initial stiffness, reflow parameters, viscosity, wettability, and mass retention, and is found to be optimal at a minimum width of 4mm, about 600-700 microns. The final reflow provided a solder thickness of 300 microns with an average width of about 10 millimeters. In these dimensions, the solder pre-form is sufficiently low in stiffness to be compatible and act as a gasket seal during manufacturing. There are two purposes, namely to help prevent the solder from oxidizing during environmental processing and to maintain a uniform gap between the substrates. The latter may be useful in reflow processes, such as those described below.

FIG. 15 is a graphical illustration of forces acting on a weld bead in an exemplary embodiment. Subscripts D and E indicate dynamic equilibrium contact angles. F is a net force based on the fact that the dynamic balance is not equal, where F ═ γ_S/V-γ_S/L-γCOS θ_D＝γ(COSθ_E-COS θD)。

Fig. 16 is a graph illustrating movement of solder as a function of gap height in an exemplary embodiment. For wettable surfaces (e.g., contact angles <90 degrees), the liquid solder moves to thinner gap heights. The opposite is true for non-wetted surfaces (e.g., contact angle >90 degrees).

In the solder reflow phase, the sum of Laplacian and clamping pressure is the driving force for the movement of the molten solder front. The ability to control solder movement and direct it to specific areas on the glass during reflow is very useful for this application. In an exemplary embodiment, the ability to direct the flow of hot capillaries through surface metallization and patterning provides a robust method for controlling solder reflow. The metal coating of the exemplary embodiment provides a medium for reactive reflow, which may also be a factor in controlling solder movement.

Spontaneous diffusion of a thick layer of molten solder between two parallel sheets of glass is described below. When the VIG unit is subjected to a linear temperature gradient, thermal capillary stress (as shown in figures 15-16),

causing and inducing movement of the solder front or contact line. If there is no reactive wetting, the solder front moves from the hot region to the cold region. However, there are other factors that play a role in the dynamic process of seal formation. The molten solder thickness or cell gap variation also determines the magnitude of the shear stress. The physical clamping makes the cell gap thinner towards the periphery of the VIG, which then flows the solder outward. In addition, as the center temperature T increases, the reaction diffusion progresses, moving the solder outward. While maintaining a constant lateral temperature gradient near the solder location, the tangential shear pressure τ acting on the solder can be calculated. The initial velocity U of the solder contact line is controlled by reactive reflow that produces a solder thickness h (t) that eventually becomes h at equilibrium (e.g., a cell gap determined by the column or space height). The inertial force on the solder is compensated by the viscosity of the solder.

From the second equation, it can be seen that the gap height and temperature gradient G have a large effect on the solder front motion. These forces may sometimes work in concert and sometimes oppose each other. However, once these factors are identified which determine, at least to some extent, the flow of solder, they can be controlled. In making a metal-sealed VIG, dark-colored metal clips or mica clips coated with black enamel frit may be used to meet the above conditions. This spatially selective modulation of emissivity helps preferentially absorb heat to the periphery of the glass and thus helps provide the temperature differential needed to form the seal.

In an inert wetting system, the Contact Line (CL) area is relatively simple. This region is geometrically characterized by a dynamic contact angle θ D. In either caseThe contact line moves under a given set of forces. In a spontaneous wetting system, uncompensated young's force F ═ γ must be included_S/V-γ_S/L-γcos θ_D＝γ(cosθ_E-cos θ_D) Orthogonal to the line of contact on the (undeformed) solid plane. It is implicitly assumed that the interface can have an equilibrium value, so S>0. The actual CL configuration during reactive wetting may depend on the reactive nature of the S/L interface on the contact line.

In an IMC formation system, a pure melt L (with atom a) is placed on a pure solid substrate S (with atom B), and L reacts with S to form AxBy. Further suppose that the solubility of B in a is much greater than that of a in B, a specific example of which is the Ag — Sn system at 240 ℃, which forms the phase AgSn 2. The intermetallic AxBy lags CL by a distance, showing that intermetallic compounds may not form on CL due to the local inability to overcome nucleation barriers on a time scale corresponding to rapid to moderate CL velocities. The configuration of CL is shown in fig. 15, however, the equilibrium state is not the same. As the system approaches equilibrium, CL slows, and as x approaches 0, the slower rate allows nucleation to occur. Quasi-equilibrium states θ can occur when the reactive products act as effective diffusion barriers on a wetted time scale₁＝θ_1,E,θ₂＝θ_2,EAnd θ P ═ θ P, E. Where θ P is the angle between the liquid/product interface and the product/solid interface at r. The driving force per unit length of CL is expressed by the following equation:

F＝γS/L(t)[γL/P/γS/L(t)cosθ_2,E-cosθ₂(t)]+γL/V(t)[γL/V/γL/V(t)cosθ_1,E-cosθ₁(t)]+γS/P(t)[γS/P/γS/P(t)cosθ_P,E-cosθ_P(t)]-G(t),

where G (t) is the change in Gibbs free energy per unit area released by the dissolution/synthesis reaction. Since G is negative for most IMC formation, the driving force is governed by the reactive reflow process.

During reflow, the solder becomes liquid and adversely wets the metallized glass. Laplacian pressure collapses the cell. Studies have shown that the peripheral seal generation and joint reliability are strongly dependent on the engineering conditions during reflow. For example, too short a time above the liquid and/or lower peak temperature may result in incomplete melting of the solder pre-form, which may adversely affect solder wetting kinetics, or may potentially form a cold joint. If the time on the liquid solder joint is too long, the peak temperature is too high and excessive intermetallic compounds may form, resulting in unreliable brittle solder joints. On the other hand, if the rate of temperature rise does not exceed the threshold, IMC formation is hindered. Therefore, from an engineering point of view, the solder wetting power has important significance for optimizing the production of metal sealing VIG engineering and the airtight reliability of welding spots.

FIG. 17 is a sequence of reactive reflow between solder and a metalized surface of glass according to an exemplary embodiment. In fig. 17, the z-axis scale is exaggerated compared to the x-axis to better illustrate the formation of IMCs.

Fig. 18 is an x-ray of a reflowed solder pre-form with a controlled wetting front at a 90 degree bend of a VIG made in accordance with an example embodiment. As shown in fig. 18, this has the advantage of having no interconnected voids in the bulk solder.

FIG. 19 is a temperature profile of a reflow process that may be used in exemplary embodiments. These two lines correspond to the temperatures measured in two different probe positions. As can be seen from fig. 19, at the contour line, the slope is nearly symmetrical or stable up and down. A relatively short temperature cycle helps to achieve sealing (even for edge sealing under ambient atmosphere). Which reduces the risk of oxidation and thus allows better control of the solder front on the centerline.

The following criteria may be used to form the hermetic seal:

the surface temperature should reach Tfs-Tm +30 ℃, where Tm is the melting point of the solder. For example, for a tin-based solder that begins to soften at 217 deg.C, the minimum thermal equilibrium temperature of the surface should be at least 247 deg.C.

The rate of change of temperature dT/dT should be around 0.5 ℃/s. It and a sufficiently high Tfs help ensure that an IMC of appropriate stoichiometry and thickness is formed with little risk of oxidation.

Uniformity of the Tfs modulus <5 ℃, e.g. to limit hot capillary forces from producing uneven reflow tin beads (e.g. according to the Marangoni effect).

The thermalization time τ should satisfy ν (D τ) > IMC thickness at Tfs. The thickness of the IMC may directly affect the stress and brittleness of the IMC. A

The coefficient of expansion of the surface coating and the solder should be matched.

After cooling, pressure should be applied as the solder cools below the contour to help ensure uniform contact between the solidified solder and the surface to which it is attached.

The seal should be held in place as it is formed to help the solder flow outward and minimize the risk of debonding during cooling.

The above applies to other possible solder systems, such as InAg with a lower TM at 150 ℃. These conditions do not in themselves ensure a long-term seal, since geometrical constraints, surface cleanliness and roughness, and the atmosphere in which the reflow is performed may have an influence on the sealing dynamics. In exemplary embodiments, the seal may be formed in air or an inert atmosphere or under vacuum, for example, depending on whether the seal is for the rim or the pump-out hole. One advantage of forming a seal under vacuum is that fewer voids can be achieved in the form of solder joints, potentially increasing the productivity of the sealed unit. In reflow soldering, a mixture of solder and flux (e.g., solder paste) may be applied to the space between the two metalized portions to be joined. Heating can then be carried out in a controlled environment by means of radiation, conduction or convection. Exposure to uv light may cause vacuum degradation due to carbonates in the glass. Therefore, getters may be used to help maintain the R-value, potentially for the life of the product.

It will be appreciated that the above may assist in forming the peripheral seal, as well as the desoldering hole seal. In relation to the latter, the ring-shaped pre-form may first be arranged concentrically with the pump hole in the metallised area. In an exemplary embodiment, when the coating is deposited on the air side of the glass, a 20 mm diameter coating may be deposited on the glass surface without a primer. Additionally, thin glass or glass of any thickness may be sprayed on the air side of the glass by the same techniques as described above (e.g., HVWC, HVOF, or the like). It allows nickel chromium to react with nickel to form a Ni-Si bond, making the adhesion of standard pull and shear tests greater than 300PSI, and the fracture occurs at the glass interface rather than within the solder/coating or solder itself. In addition, a coating layer containing silicon may be formed to increase adhesion. Reference is made to fig. 20-23. FIG. 20 is a schematic diagram of a metalized pump-out hole, where 2000 denotes a Guardian confidential VSV, in accordance with an exemplary embodiment; 2002 denotes a glass substrate; 2004, pump-out tube; 2006 denotes a three-layer film conductor; 2008 represents a wide area of metal overlapping the top conductor; 2010 represents increased sidewall metal thickness; 2012, open pores; FIG. 21 is a ring for holding a solder pre-form according to an exemplary embodiment, and FIG. 22 illustrates a feedthrough pump-out tool for a desoldering piston usable in exemplary embodiments, where 2202 represents a glass sheet; 2204 shows a piston with a vacuum adapter; 2206 shows connecting the tube to a differential pump vacuum system; 2208 represents a differentially pumped annular region; 2210 denotes an outer metal sealing surface; 2212 denotes a desoldering cover; 2214 shows connecting the tube to a vacuum system; 2216 shows the central region of the evacuation tool. The top end cap in fig. 22 may be a metallized glass or metal diaphragm in an exemplary embodiment, and may provide an optional secondary polymer seal. FIG. 23 is a mechanical drawing of a high temperature (200 ℃) compatible linear vacuum feedthrough system with a bellows-assisted seal that may be used in exemplary embodiments. The VIG unit is filled with an inert gas or mixture and heated to the softening temperature of the solder at a pressure of 100-. The source of energy may be localized radiant or resistive heating, delocalized convection, and/or the like.

The plasma may be ignited before the solder reaches the melting point to clean the VIG prior to evacuating the cell. The plasma can be struck using inductive techniques by applying a voltage between the peripheral seal and the pump-out tool or metallized shroud, when the entire cell is evacuated to 10 deg.f^-5At pressures below Torr, the voltage will slowly contact the pump-out hole region.

Sn₃Ag_0.5Cu and InAg solder pre-forms are used with metallized holesVarious topologies for achieving a desoldering seal are provided. The process typically includes solder melting, initial solder solidification, and post-solder solidification. Through several in-situ observation trials, it was found that solidification of the solder ball started on the metallized surface on the glass and spread to the top of the solder ball. From the in situ and microtissue observations, Sn₃Ag_0.5The solidification process of Cu solder balls is not uniform and is locally time-dependent regardless of their position, and it is found that the solidification start of each solder ball on a Chip Solder Package (CSP) is random. These facts indicate that solidification of each solder ball is affected by some nuclei for solidification, such as voids, inclusions, oxide films, and interfacial intermetallic compounds.

Fig. 24 is a schematic diagram of a lid with a coil-shaped solder pre-form placed over and around a pump-out hole near a metalized area of a substrate according to an example embodiment, where 2402 represents solder. In the example of fig. 24, the distance from the edge of the hole to the rightmost side of the cover may be 2 r. In an exemplary embodiment, the tube and top glass plate may be metallized. Similar to fig. 24, fig. 25 is a schematic view of a solder pre-form inserted into a pump-out hole near the metalized inside edge of the pump-out hole according to an example embodiment, where 2502 represents solder. Similar to fig. 24 and 25, fig. 26 is a schematic view of a solder pre-form inserted into a pump-out hole near the metalized inside edge of the pump-out hole, where 2602 represents solder, according to an example embodiment. In fig. 26 the pre-form may be passed through as a bead plug and the aperture and cover sheet may be preferentially wetted.

Fig. 27 shows an image of a solder bead formed by a metallized hole under vacuum.

According to the mechanical principle of seal formation, the component is heated to a temperature above the melting point of the solder and then allowed to cool. During which the solder melts and fills the gaps between the parts. The filling process depends to a large extent on the Laplacian pressure Δ P, which can be expressed as

Where Wm is the width of the metal coating and We is the gap between the connectors. For Wm>>We, Laplacian pressure is determined by

Is derived.

For highly wettable solders (0< θ < π/2), the Laplacian pressure is negative, which means that an attractive force acts between the two sheets of VIG glass. For θ > π/2, the force is repulsive. Therefore, the contact angle (and thus the control by intermolecular forces) is an important parameter, as it also controls the degree of wetting WL. WL to Wm. It should be noted that Δ P depends on T, which depends on the surface tension. This fact can be used to keep the solder in selective peripheral positions by making the edge temperature hotter than the rest of the glass.

With respect to the volume constraint of the peripheral seal, for an initial solder pre-form of dimensions Ws and ts, the volume conservation per unit length of solder can be expressed as WL < Ws X ts/We for a void-free seal.

For volume constraint of pump-out hole seal, using formula V ═ π hr²The minimum amount of solder to completely fill the cylindrical hole is obtained. Only a small fraction of this volume is required for the preparation of the gas-tight closure. The volumetric flow rate Q is derived from Q ═ Vs x P)/μ.

The reflow time τ may be expressed as τ (V/Q) x P/μ, and the volume flow rate of the solder is inversely proportional to the reflow time.

Fig. 28 is a cross-sectional view showing the pre-formation of silver indium during reactive reflow at 140 c for 4 minutes. Fig. 29 is a cross-sectional view showing the pre-formation of silver indium during reactive reflow at 150 c for 8 minutes. Fig. 30 is a high resolution XPS of InAg IMC layers formed in an exemplary embodiment.

The solderable contact can self-form by capillary action and helps ensure that the dispensed filler metal solder enters the contact. Proper joint shape design, proper adjacent surface activation, and application of the above principles help achieve the desired level of hermeticity. Further criteria that may be followed are provided below.

1. Good fit and uniform clearance

As described above, solder reflow uses the principle of capillary action to distribute molten filler metal between glass metallized surfaces. Therefore, during reflow operations, care should be taken to maintain the clearance between the glass-based metallization layers to maximize the effective wicking action. Therefore, in most example cases, clearance is desirable. Fig. 31 shows experimental data for the change in tensile strength of a solder joint as a function of joint gap thickness. In this sense, fig. 31 shows the strength of the seal compared to the gap size. This data can be illustrated by a model obtained from capillary pressure and void formation, predicting the tensile strength of the brazed joint as a function of the amount of clearance between the joining members. The seal area is substantially constant and changes in the data may be related to changes in the joint area.

The strongest contact (50MPa) is achieved with a contact clearance of about 275 microns. When the clearance is narrower, the molten solder metal may be more difficult to distribute sufficiently throughout the joint, and the joint strength may be reduced due to the formation of voids. For example, it is possible to speculate that the hermeticity of such a joint is related to its tensile strength, as long as there are no defects in the metallization coating. On the other hand, if the gap is larger than necessary, the joint strength is almost lowered to the strength of the filler metal itself. In addition, capillary action is reduced and thus the filler metal may not completely fill the joint. This may create micro-bubbles or voids, again reducing the strength of the joint and the likelihood of forming a hermetic seal. A clearance of about 275 microns for the solder joints of the two concentric cylinders (and for the exemplary VIG pump-out hole) is preferred. It should be noted that the gap set in a VIG of about 250-300 microns is the optimal range for VIG peripheral seal strength. However, in normal daily reflow, this accuracy may not be necessary to obtain a sufficiently strong and airtight joint.

In the case of a flat lid seal, the thickness of the solder need not be optimized for mechanical strength, as it can be used for gas tightness and service life. This is because the sealing is done by thermal compression. Capillary action operates in a series of gaps that open the process window. The gaps ranged from 0.025 mm to 0.130 mm, still yielding joints with tensile strengths of 10-30 MPa. The slip-susceptible fit can provide a suitable welded joint between the two tubular members. The metal-to-metal contact gap may be the total gap desired because the average "surface treatment" of the coating provides sufficient surface roughness to create a capillary "path" for the flow of the molten filler metal. However, since the IMC is also formed reactively, an optimal surface roughness window can be achieved prior to seal formation. On the other hand, if the surface is a highly polished surface, it may restrict the flow of the solder metal. This can be compensated by applying additional external pressure and active pumping. The sealed joint can be prepared at Tm temperature when the solder undergoes a phase change. Therefore, it is preferable to consider the thermal expansion coefficient of the added metal. As shown and described, a flat inclined plate made of metalized glass or metal sheet may be attached to the metalized surface in and around the pump-out hole area. Thermal compression is used for seal forming because it helps compensate for deflection or deformation, and thus non-uniform temperatures of the parts occur to form the seal.

Fig. 32 is an exemplary concentric tubular gap solderable contact that may be used in exemplary embodiments. Concentric tubular components of different metals (e.g., metal plugs or plates with respect to metallized glass) can also be joined by reactive reflow, where 3202 represents a wide gap in room temperature; 3204 denotes glass POT (metallization); 3206 indicates that the gap becomes narrower in the brazing temperature; 3208 denotes a base glass (4 mm). One example involves brazing/reflowing a brass bushing into a steel sleeve. Brass expands much more than steel when heated. Thus, if the part is machined to have a room temperature gap of 0.002-0.003 "(0.051-0.076 mm), the gap may have completely closed when the part is heated to the brazing temperature. One possible solution is to allow a larger initial gap so that the gap at the reflow temperature will reach around 80 microns. In addition, since the metal coating is deposited on the glass, it is subjected to compressive stress during heating and stretching occurs during cooling.

The degree of allowance made for expansion and contraction may depend on the nature and size of the metals being connected and the structure of the joint itself. Although in each case many variables are involved in targeting the precise gap tolerance, it is found here that the description of the different expansion rates of the metal on heating provides a good starting point for further investigation.

2. Cleaning metallized surfaces

When the metallized surface is cleaned, capillary action operates in a predictable and repeatable manner. Contaminants such as oil, grease and oxide scale are removed to achieve good results. Surface contaminants can form a barrier between the base metal surface and the braze material. For example, base metals containing oils can repel molten solder, leaving bare spots, oxidize at high temperatures and cause voids. Oils and greases carbonize when heated, forming a film over the filler metal that may not wet and flow. Cleaning of the metallized parts should be done in the correct order. The oil and grease may be removed first, followed by removal of the metal oxide. This may be accomplished by immersing the part in a suitable degreasing solvent or vapor degreasing, or the like. If the metal surface is coated with oxides or flakes, chemical and mechanical polishing may be used. To remove the chemicals, it is preferable to ensure that the chemicals are compatible with the base metal being cleaned, and that no acid traces remain in the cracks or blind vias.

Mechanical removal may require abrasive cleaning. The cleaning process may be accelerated with an abrasive cloth and then operated with an air gun. Reflow may be performed after the joining surfaces are thoroughly cleaned.

Since the formation of a VIG seal can be achieved in a vacuum, another effective method of cleaning the surface is to heat the heated surface to a vacuum environment prior to reflow, or to expose portions to a plasma glow discharge.

3. Reflow in inert atmosphere or vacuum

As the inventors have shown, vacuum treatment has the beneficial effect of forming a very low pore density seal. Connected voids and/or porosity directly affect leak rate. When reflow is performed in air, the possibility of leakage increases. Conventional fluxing agents have a corrosive effect on the metal coating and should therefore be avoided. Reflow in an inert atmosphere has proven to be another option for vacuum treatment. Which reduces the risk of leakage due to oxidation of the solder or the presence of interconnected porosity.

It is not recommended to carry out the reflow operation in air. However, there are exceptions. For example, copper-on-copper may be used in air without flux, e.g., using a filler metal solder with a moisture scavenger. (phosphorus in these alloys acts as a "flux" on the copper). It is also recommended to incorporate rare earth dopants into the solder (without changing its phase) if assembled in the atmosphere. The brazing furnace is preferably a controlled atmosphere containing a gas mixture in an enclosed space. An atmosphere (e.g., an atmosphere containing hydrogen, nitrogen, or free ammonia) may completely surround the assembly and help prevent oxidation by excluding oxygen. However, even in a controlled atmosphere, small amounts of solder paste (containing flux) have been found to improve the wetting of the solder filler metal. Finally, a vacuum environment can be used to remove any traces of organics on the filler prior to desoldering.

4. Clamping assembly for welding

The parts of the clean metal seal VIG assembly or subassembly may be positioned for reflow via peripheral mechanical or electromechanical clamping. In some cases, the linear force required is in the order of 2-5 inches/inch circumferentially. Which helps to ensure proper alignment during the heating and cooling cycles so that capillary action and reactive reflow can be used to make the seal. Uniform clamping also helps maintain a uniform air gap height with little or no wedging action. Which helps to keep the contact lines of solder within the metallised areas. The clip may be coated with a high emissivity coating to maximize the absorption of heat into the glass, particularly when a radiant oven is used.

If the arrangement is too complex to be self-supporting or clamping, a supporting fixture is preferably used. The mount can be designed with as little mass as possible and with minimal contact with the assembled components. (bulky fasteners in extensive contact with the assembly can remove heat from the contact area). Needle tip and knife edge designs are suggested to minimize contact. With respect to an exemplary support fixture that may be used in connection with the exemplary embodiment, reference is made to FIG. 33, wherein 3302 represents a support fixture having a tapered tip; 3304 shows the blade support.

The material used in the fixture may be a differential thermal conductor such as stainless steel, inconel, ceramic and mica. Because it is a weak conductor, there is minimal heat extraction from the joint on the fast time scale of seal formation. Simple mechanical retention means, even a paper clip, is preferred because it serves only to connect the parts together, and the permanent joint is made by reflow.

Plasma cleaning of VIG Chambers

VIG units generally have long term R-value stability and uv exposure time. The low temperature process of the peripheral metal seal means that extra care should be taken in degassing the unit prior to final desoldering sealing. Plasma cleaning or cleaning VIG is typically a two-step operation in which a high voltage discharge is generated in the gap after several gas cleaning cycles. Since the small gap is approximately the same size as the dark space sheath (at Pxd), it is difficult to break down and sustain a laterally capacitively coupled plasma within the VIG. However, the plasma discharge can be inductively struck at pressures as low as 200-. Remote ozone plasma can also be used to degas the VIG unit by pumping out the tool. The plasma is beneficial to removing chemically adsorbed water on the surface of the glass and organic residues in the glass. The plasma cleaning process may be performed simultaneously with the formation of the desoldering seal.

6. Solder reflow unit assembly

The realisation of the sealing joint in practice may involve heating the assembly to at least 30K above the Tm of the solder, reactively wetting the metallised surface while allowing capillary flow of the solder filler metal through the joint gap. To handle the peripheral seal, heat may be applied to the entire VIG unit; however, the area with the solder-based metal should be kept at a higher temperature. A temperature difference of at least 5K is sufficient. For example, in making small components like a desoldering seal, localized heating may be used that promotes dT/dT to be reached in the 0.5 ℃/s range and helps to keep the solder around the periphery of the cell. In the fabrication of large VIG units, heat may be selectively applied around the joints. A large amount of resistive heating in a vacuum may involve a high power heater as the size of the VIG increases. Local resistance heating may be better suited for the situation, for example, to indicate holes. Infrared heating using lamps is also an alternative since it is possible to heat the solder locally by the heat absorbed by the glass. Some solders are very good conductors and thus can transport heat to colder areas more quickly. Others are weak conductors and tend to remain hot and overheated. A good conductor may require more heat than a poor conductor simply because it dissipates heat more quickly.

It should be understood that three-layer and two-layer metal stacks may be used in connection with pump-through hole sealing embodiments. These coatings may be formed by HVOF, HVWC, and/or any other suitable technique.

The terms "heat treating" and "heat treating" as used herein mean heating the article to a temperature sufficient to achieve thermal tempering and/or thermal strengthening of the glass article. For example, this definition includes heating the coated article in an oven or furnace at a temperature of at least about 550 ℃, preferably at least about 580 ℃, and more preferably at least about 600 ℃. More preferably at least about 620 c and most preferably at least about 650 c for a time sufficient to allow tempering and/or heat strengthening. And in exemplary embodiments may be at least about two minutes, up to about 10 minutes, up to about 15 minutes, etc.

It should be noted that VIG units may be used in a number of different applications, such as residential and/or commercial window applications, skylights, merchandise, OLEDs, and/or other display devices, and the like. In various exemplary embodiments, one or both substrates of a VIG unit may be heat treated (e.g., heat strengthened and/or heat tempered). In exemplary embodiments, a laminate of glass (e.g., glass/PVB or glass/EVA) may be mated to itself or to a single sheet of glass to produce a VIG unit with or without a pump-out tube.

Although example embodiments have been described herein in connection with VIG units, it should be appreciated that the example techniques described herein may include one or more substrates formed from materials other than glass. In other words, because the exemplary techniques described herein are capable of forming a seal at lower processing times and temperatures, alternative substrate materials, such as plastic, plexiglass, etc., may be used. These materials may be used as one or both substrates in a Vacuum Insulating Panel (VIP) unit or the like as described above. Any or all of the features, aspects, techniques, configurations, etc. described above may be used for such VIP units. Further, the exemplary VIG and VIP units described herein may be laminated to another substrate in exemplary embodiments.

For example, the terms "periphery" and "edge" as used herein in relation to a seal do not mean that the seal and/or other elements are located at the absolute periphery or edge of the cell, but rather means that the seal and/or other elements are located at/at least partially at or near (e.g., within about two inches) the edge of at least one substrate of the cell. Also, as used herein, "edge" is not limited to only the absolute edge of a glass substrate, but may also include an area at or near (e.g., within about two inches) of the absolute edge of the substrate.

As used herein, unless explicitly stated, the terms "above …", "supported by …" and the like should not be construed as two elements being directly adjacent. In other words, a first layer may be said to be "on top of" or "supported by" a second layer, even if there are one or more layers therein.

In an exemplary embodiment, a method of making a Vacuum Insulated Glass (VIG) window unit is provided, the method comprising: providing a VIG unit assembly comprising first and second glass substrates; a plurality of spacers for holding the first and second glass substrates; spaced from each other substantially parallel to each other; and an edge seal, the first glass substrate having an aperture formed therein, the aperture operable to evacuate a cavity defined between the first and second glass substrates. A first multilayer thin film coating is formed on a portion of the first substrate that surrounds and/or is located on the inner diameter of the hole, the first multilayer thin film coating including at least one metal-containing layer. Disposing a solid solder alloy pre-form within and/or around the hole, the solid solder alloy pre-form being in direct physical contact with at least a portion of the first multilayer thin film coating and comprising a metal. Disposing a sealing member on and/or within the hole such that at least a portion of the sealing member is in physical contact with the solid solder alloy pre-form. In making the VIG unit, a hermetic hole seal is formed by reactively reflowing the solid solder alloy pre-form to allow diffusion of material from the first multilayer thin film coating into the solder alloy material and vice versa.

In addition to the features described in the preceding paragraph, in an exemplary embodiment, the seal member may have a second multi-layer thin film coating formed thereon, the first and second thin film coatings at least initially having the same thin film layers; and the solid solder alloy pre-form is in direct physical contact with at least a portion of the second multilayer thin film coating. Further, in exemplary embodiments, the formation of the hermetic hole seal also causes material to diffuse from the second multilayer thin film coating into the solder alloy material and vice versa, when the VIG unit is manufactured.

In addition to the features described in either of the two paragraphs above, in an exemplary embodiment the sealing member may be a plug inserted into the bore; a plate covering the hole; a plate having a plug projecting therefrom, the plate covering the aperture and the plug extending into the aperture, and/or the like.

In addition to the features described in any of the three paragraphs above, in an exemplary embodiment, the sealing member may be formed from a metal, a metal alloy, and/or glass.

In addition to the features described in any of the four paragraphs above, in an exemplary embodiment the first (and optionally the second) multilayer thin film coating may comprise a layer comprising nickel.

In addition to the features described in any of the five paragraphs above, in an exemplary embodiment the first (and optionally the second) multilayer thin film coating may comprise a layer comprising silver sandwiched between layers comprising nickel.

In addition to the features described in any of the six paragraphs above, in an exemplary embodiment, the first (and optionally the) multilayer thin film coating may comprise, in order from the surface on which it is formed: a first layer comprising silicon, a second layer comprising nickel, and a third layer comprising silver.

In addition to the features described in any of the seven paragraphs above, in an exemplary embodiment, the first (and optionally the) multilayer thin film coating may comprise, in order from the surface on which it is formed: a first layer comprising nickel and/or silicon and a second layer comprising silver.

In addition to the features described in any of the eight paragraphs above, in an exemplary embodiment, the solid solder alloy pre-form may be formed from an indium-silver alloy, SAC, Sn-Pb, SnBiAg, SATi, or SATiRE. For example, in addition to the features described in any of the eight paragraphs above, in exemplary embodiments the solid solder alloy pre-form may comprise (a) tin, silver and copper or (b) indium and silver. In addition to the features described in any of the eight paragraphs above, in an exemplary embodiment the solid solder alloy pre-form may be based on tin and comprise at least one other material selected from the group consisting of: a late transition metal or metalloid; zintl anions from group 13, 14, 15 or 16; and a transition metal.

In addition to the features described in any of the nine paragraphs above, in an exemplary embodiment, a secondary seal may be formed on and/or around the aperture.

In addition to the features described in any of the 10 paragraphs above, in an exemplary embodiment, the hole seal may be formed while the VIG unit subassembly is held under vacuum.

In addition to the features described in any of the 11 paragraphs above, in an exemplary embodiment the edge seal may be formed when the VIG unit subassembly is held at a first vacuum pressure, and the aperture seal may be formed when the VIG unit subassembly is held at a second vacuum pressure, the second vacuum pressure being lower than the first vacuum pressure.

In addition to the features described in any of the 12 paragraphs above, in an exemplary embodiment the bore seal may be formed at a temperature of no more than 300 degrees celsius (e.g., at a temperature of no more than 180 degrees celsius).

In addition to the features described in any of the 13 paragraphs above, in an exemplary embodiment, the chamber may be plasma and/or ozone purged prior to forming the hermetic hole seal and melting the solid solder alloy pre-form.

In addition to the features described in any of the 14 paragraphs above, in an exemplary embodiment, oxide generated during formation of the pore seal may be scavenged.

In addition to the features described in any of the 15 paragraphs above, in an exemplary embodiment, the pump-out tube need not be desoldered or closed in the preparation of the VIG unit.

In addition to the features described in any of the 16 paragraphs above, in an exemplary embodiment the first multilayer thin film coating may be formed in an at least partially reducing atmosphere.

In addition to the features described in any of the 17 paragraphs above, in an exemplary embodiment, the first multi-layer thin film coating may be polished to remove unwanted oxide, nitride, and/or carbon content prior to forming the aperture seal.

In addition to the features described in any of the 18 paragraphs above, in exemplary embodiments, each layer of the first multilayer thin film coating may be formed having a porosity of less than 2% and an adhesion or bond strength of at least 10 megapascals, and/or the first multilayer thin film coating may have an RMS roughness (Ra) of less than 2 micrometers and an adhesion or bond strength of at least 20 megapascals throughout.

In addition to the features described in any of the 19 paragraphs above, in an exemplary embodiment, the first and second substrates may reach a temperature sufficiently low to prevent substantial loss of temper strength during formation of the hermetic hole seal.

In addition to the features described in any of the above 20 paragraphs, in an exemplary embodiment, at least one of the substrates may be a glass substrate that is heat treated.

In addition to the features described in any of the 21 paragraphs above, in an exemplary embodiment, at least one of the substrates may be a glass substrate that is thermally tempered, and each of the glass substrates that is thermally tempered loses no more than 10% of the temper strength during the making of the VIG unit.

In addition to the features described in any of the 22 paragraphs above, in an exemplary embodiment, the hermetic hole seal may include, in order from the solid solder alloy pre-form and each side thereof: at least one intermetallic compound (IMC) layer, depositing a deposited silver-containing layer via active high energy sputtering, and depositing a deposited nickel-containing layer via active high energy sputtering.

In an exemplary embodiment, there is provided a Vacuum Insulated Glass (VIG) unit including: first and second substantially parallel spaced apart glass substrates, at least one of said first and second substrates being a heat treated glass substrate; a plurality of spacers disposed between the first and second substrates; sealing the edges; and a cavity at least partially defined by the first and second substrates and the edge seal, the cavity being evacuated to a pressure below atmospheric pressure. A hole sealing member is disposed within and/or over a hole formed in the first substrate, the hole sealing member being used to evacuate the cavity during the VIG unit preparation process. The aperture sealing member and the first substrate are hermetically sealed from each other via aperture sealing formed by reactive reflow of a metal-containing solid solder alloy preform, causing (a) diffusion of material from a pre-configured first multi-layer thin film coating on the first substrate into the solder alloy material and vice versa, and (b) formation of an intermetallic compound IMC between an uppermost layer of the first multi-layer thin film coating and the reactive reflowed solder.

In addition to the features described in the preceding paragraph, in exemplary embodiments, the first multilayer thin film coating may include a silver-containing layer deposited by active high energy jet deposition and a nickel-containing layer deposited by active high energy jet deposition, at least a portion of the first multilayer thin film coating remaining in the VIG unit.

In addition to the features described in either of the two paragraphs above, in exemplary embodiments the alloy material may include (i) tin, silver, and copper or (ii) indium and silver.

In addition to the features described in any of the three paragraphs above, in an exemplary embodiment, the hole seal may have a strength sufficient to allow the VIG unit to penetrate in a failure mode in which glass in the first substrate and/or material in the hole seal member shatters in lieu of or at least prior to failure of the hole seal.

In addition to the features described in any of the four paragraphs above, in an exemplary embodiment, at least one of the first and second substrates may be thermally tempered, each thermally tempered substrate maintaining a temper strength of at least 90% in the VIG unit.

In addition to the features described in any of the five paragraphs above, in an exemplary embodiment, the aperture sealing member may have a second pre-configured multilayer thin film coating, the first and second multilayer thin film coatings having the same layers as one another.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims (32)

1. A method of making a Vacuum Insulated Glass (VIG) window unit, the method comprising:

providing a VIG unit assembly comprising a first glass substrate and a second glass substrate; a plurality of spacers for holding the first glass substrate and the second glass substrate; spaced from each other substantially parallel to each other; and an edge seal, the first glass substrate having an aperture formed therein, the aperture operable to evacuate a cavity defined between the first and second glass substrates;

forming a first multilayer thin film coating on a portion of the first glass substrate surrounding and/or on the inner diameter of the hole, the first multilayer thin film coating comprising at least one metal-containing layer;

disposing a solid solder alloy pre-form within and/or around the hole, the solid solder alloy pre-form being in direct physical contact with at least a portion of the first multilayer thin film coating and comprising a metal;

disposing a sealing member over and/or within the hole such that at least a portion of the sealing member is in physical contact with the solid solder alloy pre-form; and

in making the VIG unit, forming a hermetic hole seal by reactively reflowing the solid solder alloy pre-form to diffuse material from the first multilayer thin film coating into the solder alloy material and vice versa;

wherein the first multilayer thin film coating comprises, in order from the surface on which it is formed: a first layer comprising silicon, a second layer comprising nickel, and a third layer comprising silver.

2. The method of claim 1, wherein the sealing member has a second multilayer thin film coating formed thereon, the first and second multilayer thin film coatings having the same layer as each other, and

the solid solder alloy pre-form is in direct physical contact with at least a portion of the second multilayer thin film coating.

3. The method of claim 2, wherein forming the hermetic hole seal also diffuses material from the second multilayer thin film coating into the solder alloy material and vice versa when making the VIG unit.

4. A method according to any of claims 1-3, wherein the sealing member is a plug inserted into the bore.

5. A method according to any of claims 1-3, wherein the sealing member is a plate covering the aperture.

6. The method of any of claims 1-3, wherein the sealing member is a plate having a plug protruding therefrom, the plate covering the aperture and the plug extending into the aperture.

7. A method according to any of claims 1-3, wherein the sealing member is formed of a metal, metal alloy and/or glass.

8. The method of any of claims 1-3, wherein the solid solder alloy pre-form is formed from an indium-silver alloy, SAC, Sn-Pb, SnBiAg, SATi, or SATiRe.

9. The method of any of claims 1-3, wherein the solid solder alloy pre-form comprises (a) tin, silver, and copper or (b) indium and silver.

10. The method of any of claims 1-3, wherein the solid solder alloy pre-form is tin-based and includes at least one other material selected from the group consisting of: a late transition metal or metalloid; zintl anions from group 13, 14, 15 or 16; and a transition metal.

11. The method of any of claims 1-3, further comprising: a secondary seal is formed on and/or around the aperture.

12. The method of any of claims 1-3, wherein the hole seal is formed while the VIG unit subassembly is held under vacuum.

13. The method of any of claims 1-3, wherein the edge seal is formed while the VIG unit subassembly is held at a first vacuum pressure, and the aperture seal is formed while the VIG unit subassembly is held at a second vacuum pressure, the second vacuum pressure being lower than the first vacuum pressure.

14. The method of any of claims 1-3, wherein the bore seal is formed at a temperature of no more than 300 degrees Celsius.

15. The method of any of claims 1-3, wherein the bore seal is formed at a temperature of no more than 180 degrees Celsius.

16. The method of any of claims 1-3, further comprising: plasma and/or ozone purging the cavity prior to forming the hermetic hole seal and melting the solid solder alloy pre-form.

17. The method of any of claims 1-3, further comprising: gettering oxide generated during formation of the pore seal.

18. The method of any of claims 1-3, wherein a pump-out tube is not required to be desoldered or closed in making the VIG unit.

19. The method of any of claims 1-3, wherein the first multilayer thin film coating is formed in an at least partially reducing atmosphere.

20. The method of any of claims 1-3, further comprising: polishing the first multi-layer thin film coating to remove unwanted oxide, nitride and/or carbon content prior to forming the aperture seal.

21. The method of any of claims 1-3, wherein each layer of the first multilayer thin film coating is formed having a porosity of less than 2% and an adhesion or bond strength of at least 10 megapascals, and/or

The first multilayer thin film coating having an RMS roughness Ra of less than 2 microns and an adhesion or bond strength of at least 20 megapascals throughout.

22. The method of any of claims 1-3, wherein the first and second glass substrates reach a sufficiently low temperature during the formation of the hermetic hole seal to prevent substantial loss of tempering strength.

23. The method of any of claims 1-3, wherein at least one of the first glass substrate and the second glass substrate is a heat-treated glass substrate.

24. The method of any of claims 1-3, wherein at least one of the first glass substrate and the second glass substrate is a thermally tempered glass substrate, and each of the glass substrates that are thermally tempered loses no more than 10% of their temper strength during the making of the VIG unit.

25. The method of any of claims 1-3, wherein the hermetic hole seal comprises, in order from the solid solder alloy pre-form and each side thereof: at least one intermetallic IMC layer, a silver-containing layer deposited by active high energy jet deposition, and a nickel-containing layer deposited by active high energy jet deposition.

26. A vacuum insulating glass, VIG, unit made by using the method of any of claims 1-25.

27. A vacuum insulating glass, VIG, unit comprising:

a first glass substrate and a second glass substrate spaced substantially parallel, at least one of the first glass substrate and the second glass substrate being a heat treated glass substrate;

a plurality of spacers disposed between the first glass substrate and the second glass substrate;

sealing the edges;

a cavity defined at least in part by the first and second glass substrates and the edge seal, the cavity being evacuated to a pressure below atmospheric pressure; and

a hole sealing member disposed within and/or over a hole formed in the first glass substrate, the hole sealing member being used to evacuate the cavity during the VIG unit manufacturing process, the hole sealing member and the first glass substrate being hermetically sealed to one another via hole sealing, the hole sealing being formed by reactive reflow of a metal-containing solid solder alloy preform, causing (a) diffusion of material from a preconfigured first multilayer thin film coating on the first glass substrate into the solder alloy material, and vice versa, and (b) an intermetallic compound IMC to be formed between an uppermost layer of the first multilayer thin film coating and the reactive reflowed solder;

wherein the first multilayer thin film coating comprises, in order from the surface on which it is formed: a first layer comprising silicon, a second layer comprising nickel, and a third layer comprising silver.

28. The VIG unit of claim 27, wherein the first multilayer thin film coating comprises a silver-containing layer deposited by active high energy jet deposition and a nickel-containing layer deposited by active high energy jet deposition, at least a portion of the first multilayer thin film coating remaining in the VIG unit.

29. The VIG unit of any of claims 27-28, wherein the alloy material comprises (i) tin, silver, and copper or (ii) indium and silver.

30. The VIG unit of any of claims 27-28, wherein the hole seal has sufficient strength to allow the VIG unit to penetrate in a failure mode in which glass in the first glass substrate and/or material in the hole seal member shatters in lieu of or at least prior to failure of the hole seal.

31. The VIG unit of any of claims 27-28, wherein at least one of the first and second glass substrates is thermally tempered, each thermally tempered glass substrate maintaining a temper strength of at least 90% in the VIG unit.

32. The VIG unit of any of claims 27-28, wherein the aperture sealing member has a preconfigured second multi-layer thin film coating, the first and second multi-layer thin film coatings having the same layers as one another.

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